126-522: A calutron is a mass spectrometer originally designed and used for separating the isotopes of uranium . It was developed by Ernest Lawrence during the Manhattan Project and was based on his earlier invention, the cyclotron . Its name was derived from California University Cyclotron, in tribute to Lawrence's institution, the University of California , where it was invented. Calutrons were used in
252-423: A British Mission headed by Oliphant that included fellow Australian physicists Harrie Massey and Eric Burhop , and British physicists such as Joan Curran and Thomas Allibone . Lawrence had a large cyclotron under construction at Berkeley, one with a 184-inch (470 cm) magnet. This was converted into a calutron that was switched on for the first time on 26 May 1942. Like the 37-inch version, it looked like
378-466: A fractal surface, such as rocks or soil, and are used by navigation radars. A radar beam follows a linear path in vacuum but follows a somewhat curved path in atmosphere due to variation in the refractive index of air, which is called the radar horizon . Even when the beam is emitted parallel to the ground, the beam rises above the ground as the curvature of the Earth sinks below the horizon. Furthermore,
504-403: A receiver and processor to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds. Radar was developed secretly for military use by several countries in the period before and during World War II . A key development was the cavity magnetron in
630-424: A transmitter that emits radio waves known as radar signals in predetermined directions. When these signals contact an object they are usually reflected or scattered in many directions, although some of them will be absorbed and penetrate into the target. Radar signals are reflected especially well by materials of considerable electrical conductivity —such as most metals, seawater , and wet ground. This makes
756-547: A 200-tank section of a production plant. Between October 1942 and November 1943, Groves paid monthly visits to the Radiation Laboratory in Berkeley. Reports indicated that compared to the alternatives of a gaseous diffusion plant or a plutonium -producing nuclear reactor , an electromagnetic plant would take longer and require more scarce materials to build, and need more manpower and more electricity to operate. The cost of
882-455: A 24-fold magnification of the XA calutron that could hold 96 calutron Alpha tanks. The calutrons were upright and arrayed facing each other in pairs of inner and outer machines. To minimize magnetic losses, and to economize on steel consumption, the assembly was curved into an oval shape that formed a closed magnetic loop 122 feet (37 m) long, 77 feet (23 m) wide and 15 feet (4.6 m) high, in
1008-420: A bomb by mid-1943, based on new estimates from Robert Oppenheimer that the critical mass of a sphere of pure uranium-235 was between 2.0 and 2.5 kilograms. The experiments with the 184-inch magnet led to the construction of a prototype calutron called the XA. It contained a rectangular, three-coil magnet with a horizontal field in which the calutron tanks could stand side by side, with four vacuum tanks, each with
1134-482: A different dielectric constant or diamagnetic constant from the first, the waves will reflect or scatter from the boundary between the materials. This means that a solid object in air or in a vacuum , or a significant change in atomic density between the object and what is surrounding it, will usually scatter radar (radio) waves from its surface. This is particularly true for electrically conductive materials such as metal and carbon fibre, making radar well-suited to
1260-703: A double source. At the 25 June 1942 meeting of the S-1 Executive Committee, which had superseded the S-1 Uranium Committee on 19 June, there was a proposal to build the electromagnetic plant at Oak Ridge, where the other Manhattan Project uranium separation facilities would be located, for reasons of economy and security. Lawrence lodged an objection due to his desire to have the electromagnetic separation plant located much nearer to Berkeley. The Shasta Dam area in California remained under consideration for
1386-535: A full radar system, that he called a telemobiloscope . It operated on a 50 cm wavelength and the pulsed radar signal was created via a spark-gap. His system already used the classic antenna setup of horn antenna with parabolic reflector and was presented to German military officials in practical tests in Cologne and Rotterdam harbour but was rejected. In 1915, Robert Watson-Watt used radio technology to provide advance warning of thunderstorms to airmen and during
SECTION 10
#17328693647961512-425: A giant C when viewed from above. The operator sat in the open end, whence the temperature could be regulated, the position of the electrodes adjusted, and even components replaced through an airlock while it was running. The new, more powerful calutron was not used to produce enriched uranium, but for experiments with multiple ion sources. This meant having more collectors, but it multiplied the throughput. The problem
1638-442: A kilogram of fissile material would therefore be much greater. On the other hand, while the alternative processes still faced considerable technical obstacles, the electromagnetic process was proven to work, and could be built in stages that would immediately start producing fissile material. Groves cancelled the pilot plant on 14 November, in favor of proceeding immediately with the production plant. The Radiation Laboratory forwarded
1764-669: A magnetic field, and lighter ones are deflected more than heavy ones. The reason the Maud Committee, and later its American counterpart, the S-1 Section of the Office of Scientific Research and Development (OSRD), had passed over the electromagnetic method was that while the mass spectrometer was capable of separating isotopes, it produced very low yields. The reason for this was the so-called space charge limitation. Positive ions have positive charge, so they tend to repel each other, which causes
1890-880: A monthly accounting to the Treasury. The 1,000-troy-ounce (31 kg) silver bars were taken under guard to the Defense Plant Corporation in Carteret, New Jersey , where they were cast into cylindrical billets, and then to Phelps Dodge in Bayway, New Jersey , where they were extruded into strips 0.625 inches (15.9 mm) thick, 3 inches (7.6 cm) wide and 40 feet (12 m) long. Some 258 carloads were shipped under guard by rail to Allis-Chalmers in Milwaukee, Wisconsin , where they were wound onto magnetic coils and sealed into welded casings. Finally, they moved by unguarded flatcars to
2016-729: A physics instructor at the Imperial Russian Navy school in Kronstadt , developed an apparatus using a coherer tube for detecting distant lightning strikes. The next year, he added a spark-gap transmitter . In 1897, while testing this equipment for communicating between two ships in the Baltic Sea , he took note of an interference beat caused by the passage of a third vessel. In his report, Popov wrote that this phenomenon might be used for detecting objects, but he did nothing more with this observation. The German inventor Christian Hülsmeyer
2142-405: A plate and produce a measurable electric current . Since the ions of the different isotopes have the same electric charge but different masses, the heavier isotopes are deflected less by the magnetic field, causing the beam of particles to separate into several beams by mass, striking the plate at different locations. The mass of the ions can be calculated according to the strength of the field and
2268-443: A production race and Lawrence lost, a morale boost for the " Calutron Girls " (called Cubicle Operators at the time) and their supervisors. The women were trained like soldiers not to reason why, while "the scientists could not refrain from time-consuming investigation of the cause of even minor fluctuations of the dials". For a while, the calutrons suffered from a series of debilitating breakdowns and equipment failures, exacerbated by
2394-495: A proposal for further intensive research on radio-echo signals from moving targets to take place at NRL, where Taylor and Young were based at the time. Similarly, in the UK, L. S. Alder took out a secret provisional patent for Naval radar in 1928. W.A.S. Butement and P. E. Pollard developed a breadboard test unit, operating at 50 cm (600 MHz) and using pulsed modulation which gave successful laboratory results. In January 1931,
2520-698: A pulsed system, and the first such elementary apparatus was demonstrated in December 1934 by the American Robert M. Page , working at the Naval Research Laboratory . The following year, the United States Army successfully tested a primitive surface-to-surface radar to aim coastal battery searchlights at night. This design was followed by a pulsed system demonstrated in May 1935 by Rudolf Kühnhold and
2646-442: A rescue. For similar reasons, objects intended to avoid detection will not have inside corners or surfaces and edges perpendicular to likely detection directions, which leads to "odd" looking stealth aircraft . These precautions do not totally eliminate reflection because of diffraction , especially at longer wavelengths. Half wavelength long wires or strips of conducting material, such as chaff , are very reflective but do not direct
SECTION 20
#17328693647962772-651: A shortage of spare parts. Hopes that the Alpha II racetracks would be more reliable soon faded, as they were plagued by insulator failures. These problems were gradually overcome. The first shipments of enriched uranium to the Manhattan Project's Los Alamos Laboratory were made in March 1944, consisting of Alpha product enriched to 13 to 15 percent uranium-235. While of no use in a bomb, it was urgently required for experiments with enriched uranium. The last shipment of Alpha product
2898-662: A system might do, Wilkins recalled the earlier report about aircraft causing radio interference. This revelation led to the Daventry Experiment of 26 February 1935, using a powerful BBC shortwave transmitter as the source and their GPO receiver setup in a field while a bomber flew around the site. When the plane was clearly detected, Hugh Dowding , the Air Member for Supply and Research , was very impressed with their system's potential and funds were immediately provided for further operational development. Watson-Watt's team patented
3024-480: A total of 288 calutrons, although only 216 of them were ever operated. Work on the new Beta process building commenced on 20 October 1943. Equipment installation began on 1 April 1944, and it was ready for use on 10 September 1944. A third Beta process building, 9204-3, was authorized in May 1944 to process the output of the K-25 gaseous diffusion plant. It was completed on 15 May 1945. A fourth Beta process building, 9204-4,
3150-514: A wide region and direct fighter aircraft towards targets. Marine radars are used to measure the bearing and distance of ships to prevent collision with other ships, to navigate, and to fix their position at sea when within range of shore or other fixed references such as islands, buoys, and lightships. In port or in harbour, vessel traffic service radar systems are used to monitor and regulate ship movements in busy waters. Meteorologists use radar to monitor precipitation and wind. It has become
3276-522: A worker from exposure to phosgene also prompted a search for a safer production process. In February 1945, slightly enriched 1.4 percent uranium-235 feed material began arriving from the S-50 liquid thermal diffusion plant . Shipments of product from S-50 were discontinued in April. S-50 product was fed into K-25 instead. In March 1945, Y-12 began receiving feed enriched to 5 percent from K-25. The output of these plants
3402-855: A writeup on the apparatus was entered in the Inventions Book maintained by the Royal Engineers. This is the first official record in Great Britain of the technology that was used in coastal defence and was incorporated into Chain Home as Chain Home (low) . Before the Second World War , researchers in the United Kingdom, France , Germany , Italy , Japan , the Netherlands , the Soviet Union , and
3528-452: Is a simplification for transmission in a vacuum without interference. The propagation factor accounts for the effects of multipath and shadowing and depends on the details of the environment. In a real-world situation, pathloss effects are also considered. Frequency shift is caused by motion that changes the number of wavelengths between the reflector and the radar. This can degrade or enhance radar performance depending upon how it affects
3654-451: Is as follows, where F D {\displaystyle F_{D}} is Doppler frequency, F T {\displaystyle F_{T}} is transmit frequency, V R {\displaystyle V_{R}} is radial velocity, and C {\displaystyle C} is the speed of light: Passive radar is applicable to electronic countermeasures and radio astronomy as follows: Only
3780-560: Is intended. Radar relies on its own transmissions rather than light from the Sun or the Moon, or from electromagnetic waves emitted by the target objects themselves, such as infrared radiation (heat). This process of directing artificial radio waves towards objects is called illumination , although radio waves are invisible to the human eye as well as optical cameras. If electromagnetic waves travelling through one material meet another material, having
3906-588: Is that?" he asked. In fact I did not know how to convert tons to troy ounces, and neither did he. A little impatient, I responded, "I don't know how many troy ounces we need but I know I need six thousand tons—that is a definite quantity. What difference does it make how we express the quantity?" He replied rather indignantly, "Young man, you may think of silver in tons, but the Treasury will always think of silver in troy ounces." Eventually, 14,700 short tons (13,300 tonnes; 430,000,000 troy ounces) of silver were used, then worth over $ 600 million. Nichols had to provide
Calutron - Misplaced Pages Continue
4032-417: Is the range. This yields: This shows that the received power declines as the fourth power of the range, which means that the received power from distant targets is relatively very small. Additional filtering and pulse integration modifies the radar equation slightly for pulse-Doppler radar performance , which can be used to increase detection range and reduce transmit power. The equation above with F = 1
4158-576: The Atomic Energy Commission for permission to use the Beta calutrons to produce isotopes for physics experiments. Permission was granted, and a wide range of isotopes was produced. Lithium-6 from the Beta calutrons was used for research into thermonuclear weapons . Many other isotopes were used for peaceful scientific and medical purposes. The Beta 3 racetracks were transferred to the ORNL in March 1950. By
4284-548: The Clinton Engineer Works in Oak Ridge, Tennessee . By the middle of 1944, there were nearly 1,200 people working at the Radiation Laboratory. Much of the great progress on the electromagnetic process can be attributed to Lawrence's leadership style. His audacity, optimism and enthusiasm were contagious. His staff put in long hours, and University of California administrators sliced through red tape despite not knowing what
4410-753: The Commissariat à l'énergie atomique et aux énergies alternatives in Bruyères-le-Châtel . Israel, Japan and France also built some research calutrons, including the SOLIS and MEIRA separators at the Soreq Nuclear Research Center . There is also CERN 's Isotope Separator On-Line Detector (ISOLDE), which was built in 1967. A calutron at the Saha Institute of Nuclear Physics at Bidhan Nagar in India
4536-623: The Nyquist frequency , since the returned frequency otherwise cannot be distinguished from shifting of a harmonic frequency above or below, thus requiring: Or when substituting with F D {\displaystyle F_{D}} : As an example, a Doppler weather radar with a pulse rate of 2 kHz and transmit frequency of 1 GHz can reliably measure weather speed up to at most 150 m/s (340 mph), thus cannot reliably determine radial velocity of aircraft moving 1,000 m/s (2,200 mph). In all electromagnetic radiation ,
4662-714: The RAF's Pathfinder . The information provided by radar includes the bearing and range (and therefore position) of the object from the radar scanner. It is thus used in many different fields where the need for such positioning is crucial. The first use of radar was for military purposes: to locate air, ground and sea targets. This evolved in the civilian field into applications for aircraft, ships, and automobiles. In aviation , aircraft can be equipped with radar devices that warn of aircraft or other obstacles in or approaching their path, display weather information, and give accurate altitude readings. The first commercial device fitted to aircraft
4788-1262: The United Kingdom , which allowed the creation of relatively small systems with sub-meter resolution. The term RADAR was coined in 1940 by the United States Navy as an acronym for "radio detection and ranging". The term radar has since entered English and other languages as an anacronym , a common noun, losing all capitalization . The modern uses of radar are highly diverse, including air and terrestrial traffic control, radar astronomy , air-defense systems , anti-missile systems , marine radars to locate landmarks and other ships, aircraft anti-collision systems, ocean surveillance systems, outer space surveillance and rendezvous systems, meteorological precipitation monitoring, radar remote sensing , altimetry and flight control systems , guided missile target locating systems, self-driving cars , and ground-penetrating radar for geological observations. Modern high tech radar systems use digital signal processing and machine learning and are capable of extracting useful information from very high noise levels. Other systems which are similar to radar make use of other parts of
4914-512: The University of Birmingham in Britain, the Australian physicist Mark Oliphant assigned two refugee physicists—Otto Frisch and Rudolf Peierls —the task of investigating the feasibility of an atomic bomb, ironically because their status as enemy aliens precluded their working on secret projects like radar . Their March 1940 Frisch–Peierls memorandum indicated that the critical mass of uranium-235
5040-440: The electromagnetic spectrum . One example is lidar , which uses predominantly infrared light from lasers rather than radio waves. With the emergence of driverless vehicles, radar is expected to assist the automated platform to monitor its environment, thus preventing unwanted incidents. As early as 1886, German physicist Heinrich Hertz showed that radio waves could be reflected from solid objects. In 1895, Alexander Popov ,
5166-407: The reflective surfaces . A corner reflector consists of three flat surfaces meeting like the inside corner of a cube. The structure will reflect waves entering its opening directly back to the source. They are commonly used as radar reflectors to make otherwise difficult-to-detect objects easier to detect. Corner reflectors on boats, for example, make them more detectable to avoid collision or during
Calutron - Misplaced Pages Continue
5292-527: The "new boy" Arnold Frederic Wilkins to conduct an extensive review of available shortwave units. Wilkins would select a General Post Office model after noting its manual's description of a "fading" effect (the common term for interference at the time) when aircraft flew overhead. By placing a transmitter and receiver on opposite sides of the Potomac River in 1922, U.S. Navy researchers A. Hoyt Taylor and Leo C. Young discovered that ships passing through
5418-413: The 1920s went on to lead the U.K. research establishment to make many advances using radio techniques, including the probing of the ionosphere and the detection of lightning at long distances. Through his lightning experiments, Watson-Watt became an expert on the use of radio direction finding before turning his inquiry to shortwave transmission. Requiring a suitable receiver for such studies, he told
5544-672: The American project was smaller than the British, and not as far advanced. A disappointed Oliphant flew to the United States to speak to the American scientists. These included Ernest Lawrence at the University of California 's Radiation Laboratory in Berkeley . The two men had met before the war, and were friends. Lawrence was sufficiently impressed to commence his own research into uranium. Uranium-235 makes up only about 0.72% of natural uranium, so
5670-482: The Beta calutrons. Extraordinary efforts were made to recover product, including burning the carbon receiver liners to recover the uranium in them. Despite everything, some 17.4 percent of Alpha product and 5.4 percent of Beta product was lost. Frank Spedding from the Manhattan Project's Ames Laboratory and Philip Baxter from the British Mission were sent to advise on improvements to recovery methods. The death of
5796-703: The Beta racetracks turned out another 953 kilograms enriched to 95 percent by the end of the year. Enriched uranium from the calutrons provided the fissile component of the Little Boy atomic bomb used in the atomic bombing of Hiroshima in August 1945. With the war over, the Alpha tracks began to suspend operations on 4 September 1945, and ceased operation completely on 22 September. The last two Beta tracks went into full operation in November and December 1945, processing feed from K-25 and
5922-694: The China Institute of Atomic Energy in Beijing of identical design to those of the USSR in the early 1960s. In 1945, the British atomic bomb project built a 180° calutron, similar in design to an American Beta calutron, at the Atomic Energy Research Establishment at Harwell, Oxfordshire . Owing to the success of the gaseous diffusion plant at Capenhurst , electromagnetic separation was not pursued by
6048-498: The Clinton Engineer Works. There, special procedures were instituted for handling the silver. When they had to drill holes in it, they did so over paper so that the filings could be collected. After the war, all the machinery was dismantled and cleaned and the floorboards beneath the machinery were ripped up and burned to recover minute amounts of silver. In the end, 155,645.39 troy ounces (4,841.113 kg) or less than 0.036%
6174-710: The Oak Ridge township was selected in the hope that the surrounding ridge lines might contain a major explosion or nuclear accident. Problems with the substratum required the excavation crews to perform more blasting and excavation to provide adequate foundations for the heavy machinery in the facilities. Supplies and materials of all kinds poured in: 2,157 carloads of electrical equipment, 1,219 of heavy equipment, 5,389 of lumber, 1,407 of pipe and fittings, 1,188 of steel, 257 of valves, and 11 of welding electrodes. The racetracks required 85,000 vacuum tubes . Where possible, off-the-shelf components were used, but all too many components of
6300-539: The United Kingdom, and the calutron was used to separate isotopes for research. The 180° design was not ideal for this purpose, so Harwell built a 90° calutron, HERMES, the "Heavy Elements and Radioactive Material Electromagnetic Separator". It was inspired by France's SIDONIE and PARIS separators at the Laboratoire René Bernas of the University of Paris IX in Orsay , and PARSIFAL at the military research laboratory of
6426-507: The United States by Niels Bohr . Based on his liquid drop model of the nucleus, he theorized that it was the uranium-235 isotope and not the more abundant uranium-238 that was primarily responsible for fission with thermal neutrons . To verify this Alfred O. C. Nier at the University of Minnesota used a mass spectrometer to create a microscopic amount of enriched uranium-235 in April 1940. John R. Dunning , Aristid von Grosse and Eugene T. Booth were then able to confirm that Bohr
SECTION 50
#17328693647966552-407: The United States into World War II , a uranium beam intensity of 5 microamperes (μA) was received by the collector. Lawrence's hunch about the effect of the air molecules in the vacuum chamber was confirmed. A nine-hour run on 14 January 1942 with a 50 μA beam produced 18 micrograms (μg) of uranium enriched to 25% uranium-235, about ten times as much as Nier had produced. By February, improvements in
6678-714: The United States, independently and in great secrecy, developed technologies that led to the modern version of radar. Australia, Canada, New Zealand, and South Africa followed prewar Great Britain's radar development, Hungary and Sweden generated its radar technology during the war. In France in 1934, following systematic studies on the split-anode magnetron , the research branch of the Compagnie générale de la télégraphie sans fil (CSF) headed by Maurice Ponte with Henri Gutton, Sylvain Berline and M. Hugon, began developing an obstacle-locating radio apparatus, aspects of which were installed on
6804-508: The Wikimedia System Administrators, please include the details below. Request from 172.68.168.226 via cp1108 cp1108, Varnish XID 825841662 Upstream caches: cp1108 int Error: 429, Too Many Requests at Fri, 29 Nov 2024 08:36:05 GMT Radar Radar is a system that uses radio waves to determine the distance ( ranging ), direction ( azimuth and elevation angles ), and radial velocity of objects relative to
6930-533: The arrest of Oshchepkov and his subsequent gulag sentence. In total, only 607 Redut stations were produced during the war. The first Russian airborne radar, Gneiss-2 , entered into service in June 1943 on Pe-2 dive bombers. More than 230 Gneiss-2 stations were produced by the end of 1944. The French and Soviet systems, however, featured continuous-wave operation that did not provide the full performance ultimately synonymous with modern radar systems. Full radar evolved as
7056-475: The beam path caused the received signal to fade in and out. Taylor submitted a report, suggesting that this phenomenon might be used to detect the presence of ships in low visibility, but the Navy did not immediately continue the work. Eight years later, Lawrence A. Hyland at the Naval Research Laboratory (NRL) observed similar fading effects from passing aircraft; this revelation led to a patent application as well as
7182-438: The beam to scatter. Drawing on his experience with the precise control of charged-particle beams from his work with his invention, the cyclotron , Lawrence suspected that the air molecules in the vacuum chamber would neutralize the ions, and create a focused beam. Oliphant inspired Lawrence to convert his old 37-inch (94 cm) cyclotron into a giant mass spectrometer for isotope separation . The 37-inch cyclotron at Berkeley
7308-410: The calutrons of the Manhattan Project were dismantled at the end of the war, some remained in use to produce isotopically enriched samples of naturally occurring elements for military, scientific and medical purposes. News of the discovery of nuclear fission by German chemists Otto Hahn and Fritz Strassmann in 1938, and its theoretical explanation by Lise Meitner and Otto Frisch , was brought to
7434-565: The calutrons were unique. Two purchasing departments were established, one in Boston near Stone & Webster for facility equipment, and the other at Oak Ridge for construction supplies. The Chief Engineer of the Manhattan District, Colonel James C. Marshall , and his deputy, Lieutenant Colonel Kenneth D. Nichols , discovered that the electromagnetic isotope separation process would require 5,000 short tons (4,500 tonnes) of copper , which
7560-406: The characteristics of electric discharges in magnetic fields, today known as Bohm diffusion . Their papers on the properties of plasmas under magnetic containment would find usage in the post-war world in research into controlled nuclear fusion . Other technical problems were more mundane but no less important. Although the beams had low intensity, they could, over many hours of operation, still melt
7686-417: The charge of the ions. During World War II , calutrons were developed to use this principle to obtain substantial quantities of high-purity uranium-235, by taking advantage of the small mass difference between uranium isotopes. Electromagnetic separation for uranium enrichment was abandoned in the post-war period in favor of the more complicated, but more efficient, gaseous diffusion method. Although most of
SECTION 60
#17328693647967812-592: The collectors. A water cooling system was therefore added to the collectors and the tank liner. Procedures were developed for cleaning the "gunk" that condensed inside the vacuum tank. A particular problem was blockage of the slits by "crud", which caused the ion beams to lose focus, or stop entirely. The chemists had to find a way of producing quantities of uranium tetrachloride ( UCl 4 ) from uranium oxide . (Nier had used uranium bromide.) Initially, they produced it by using hydrogen to reduce uranium trioxide ( UO 3 ) to uranium dioxide ( UO 2 ), which
7938-582: The construction of five Alpha and two Beta racetracks. In September, he authorized four more Alpha racetracks, which became known as Alpha II, along with two more Beta racetracks to process their product. Construction of the electromagnetic plant at Oak Ridge, codenamed Y-12 , commenced 18 February 1943. The facility would eventually comprise nine major process buildings and 200 other structures covering almost 80 acres (32 ha) of floor space. The 825-acre (334 ha) site in Bear Creek Valley southwest of
8064-638: The contracts with the University of California from the OSRD until 1 May 1943. Major Thomas T. Crenshaw, Jr., became California Area Engineer in August 1942, with Captain Harold A. Fidler , who soon replaced him, as his assistant. Crenshaw established his office in the Donner Laboratory at the University of California. In September 1942, the S-1 Executive Committee recommended that a five-tank pilot plant be built along with
8190-408: The detection of aircraft and ships. Radar absorbing material , containing resistive and sometimes magnetic substances, is used on military vehicles to reduce radar reflection . This is the radio equivalent of painting something a dark colour so that it cannot be seen by the eye at night. Radar waves scatter in a variety of ways depending on the size (wavelength) of the radio wave and the shape of
8316-471: The detection process. As an example, moving target indication can interact with Doppler to produce signal cancellation at certain radial velocities, which degrades performance. Sea-based radar systems, semi-active radar homing , active radar homing , weather radar , military aircraft, and radar astronomy rely on the Doppler effect to enhance performance. This produces information about target velocity during
8442-411: The detection process. This also allows small objects to be detected in an environment containing much larger nearby slow moving objects. Doppler shift depends upon whether the radar configuration is active or passive. Active radar transmits a signal that is reflected back to the receiver. Passive radar depends upon the object sending a signal to the receiver. The Doppler frequency shift for active radar
8568-606: The device in patent GB593017. Development of radar greatly expanded on 1 September 1936, when Watson-Watt became superintendent of a new establishment under the British Air Ministry , Bawdsey Research Station located in Bawdsey Manor , near Felixstowe, Suffolk. Work there resulted in the design and installation of aircraft detection and tracking stations called " Chain Home " along the East and South coasts of England in time for
8694-538: The electric field is perpendicular to the direction of propagation, and the electric field direction is the polarization of the wave. For a transmitted radar signal, the polarization can be controlled to yield different effects. Radars use horizontal, vertical, linear, and circular polarization to detect different types of reflections. For example, circular polarization is used to minimize the interference caused by rain. Linear polarization returns usually indicate metal surfaces. Random polarization returns usually indicate
8820-450: The electromagnetic plant until September 1942, by which time Lawrence had dropped his objection. The 25 June meeting also designated Stone & Webster as the primary contractor for the design and engineering. The Army assumed responsibility for the Manhattan Project on 17 September 1942, with Brigadier General Leslie R. Groves, Jr. , as director, although the Army did not formally take over
8946-459: The electromagnetic process, $ 18 million (92 percent) was spent at the Radiation Laboratory in Berkeley, and further work conducted at Brown University , Johns Hopkins University and Purdue University , and by the Tennessee Eastman corporation. During 1943, the emphasis shifted from research to development, engineering, and the training of workers to operate the production facilities at
9072-473: The entire area in front of it, and then used one of Watson-Watt's own radio direction finders to determine the direction of the returned echoes. This fact meant CH transmitters had to be much more powerful and have better antennas than competing systems but allowed its rapid introduction using existing technologies. A key development was the cavity magnetron in the UK, which allowed the creation of relatively small systems with sub-meter resolution. Britain shared
9198-461: The firm GEMA [ de ] in Germany and then another in June 1935 by an Air Ministry team led by Robert Watson-Watt in Great Britain. In 1935, Watson-Watt was asked to judge recent reports of a German radio-based death ray and turned the request over to Wilkins. Wilkins returned a set of calculations demonstrating the system was basically impossible. When Watson-Watt then asked what such
9324-491: The form of a box with a slit in it and hot filaments inside. Uranium tetrachloride was ionized by the filament, and then passed through a 0.04-by-2-inch (1.0 by 50.8 mm) slot into a vacuum chamber. The magnet was then used to deflect the ion beam by 180°. The enriched and depleted beams went into collectors. When the calutron was first operated on 2 December 1941, just days before the Japanese attack on Pearl Harbor brought
9450-436: The gaseous diffusion process, uranium tetrachloride is hygroscopic , so work with it had to be undertaken in gloveboxes that were kept dry with phosphorus pentoxide ( P 4 O 10 ). The presence of phosgene, a lethal gas responsible for 85,000 deaths as a chemical weapon during World War I , required that the chemists wear gas masks when handling it. Of the $ 19.6 million spent on research and development of
9576-543: The gaseous diffusion process. Uranium enriched to about 40 percent uranium-235 was brought to Sverdlovsk-45 for final enrichment to between 92 and 98 percent. After the problems with the gaseous diffusion process were resolved in 1950, it was decided not to proceed with a full-scale electromagnetic plant. As of 2009, it remains operational. In 1969, a research calutron known as S-2 was built at Arzamas-16 for high-efficiency separation of isotopes of heavy elements like plutonium. Four research and production calutrons were built at
9702-412: The greater success of the calutron, work was discontinued and the team was transferred to other duties. At Cornell University a group under Lloyd P. Smith that included William E. Parkins, and A. Theodore Forrester devised a radial magnetic separator. They were surprised that their beams were more precise than expected, and, like Lawrence, deduced that it was a result of stabilization of the beam by air in
9828-454: The industrial-scale Y-12 uranium enrichment plant at the Clinton Engineer Works in Oak Ridge, Tennessee . The enriched uranium produced was used in the Little Boy atomic bomb that was detonated over Hiroshima on 6 August 1945. The calutron is a type of sector mass spectrometer , an instrument in which a sample is ionized and then accelerated by electric fields and deflected by magnetic fields . The ions ultimately collide with
9954-488: The mid-1950s, the Beta calutrons had produced quantities of all the naturally occurring stable isotopes except those of osmium , which had to wait until April 1960. The calutrons continued to produce isotopes until 1998. As of 2015, they are still on standby. Like the United States, the Soviet Union (USSR) carried out research on multiple enrichment technologies for the Soviet atomic bomb project . A trial electromagnetic process
10080-452: The most important being that they had four sources instead of just two. They also had improved magnets and vacuum systems. Tennessee Eastman was hired to manage Y-12 on the usual cost plus fixed fee basis, with a fee of $ 22,500 per month plus $ 7,500 per racetrack for the first seven racetracks and $ 4,000 per additional racetrack. Workers were recruited in the Knoxville area. The typical recruit
10206-418: The new K-27 gaseous diffusion plant. By May 1946, studies suggested that the gaseous diffusion plants could fully enrich the uranium by themselves without accidentally creating a critical mass. After a trial demonstrated that this was the case, Groves ordered all but one Beta track shut down in December 1946. The total cost of the electromagnetic project up to the end of the Manhattan Project on 31 December 1946
10332-494: The ocean liner Normandie in 1935. During the same period, Soviet military engineer P.K. Oshchepkov , in collaboration with the Leningrad Electrotechnical Institute , produced an experimental apparatus, RAPID, capable of detecting an aircraft within 3 km of a receiver. The Soviets produced their first mass production radars RUS-1 and RUS-2 Redut in 1939 but further development was slowed following
10458-542: The old Beta chemistry building, 9203, was converted into a laboratory. Work started on the new Alpha II process buildings on 2 November 1943; the first racetrack was completed in July 1944, and all four were operational by 1 October 1944. The Alpha II racetracks were configured in a linear layout rather than an oval, although they were still called racetracks. In all, there were 864 Alpha calutrons, arranged in nine racetracks of 96. There were only 36 calutrons in each Beta racetrack, for
10584-520: The outbreak of World War II in 1939. This system provided the vital advance information that helped the Royal Air Force win the Battle of Britain ; without it, significant numbers of fighter aircraft, which Great Britain did not have available, would always have needed to be in the air to respond quickly. The radar formed part of the " Dowding system " for collecting reports of enemy aircraft and coordinating
10710-471: The preliminary designs for a production plant to Stone & Webster before the end of the year, but one important issue remained unsettled. Oppenheimer contended that weapons-grade uranium would have to be 90% pure uranium-235. Edward Lofgren and Martin Kamen thought that this could not be achieved without a second stage of enrichment. The two stages became known as Alpha and Beta. In March 1943, Groves approved
10836-706: The primary tool for short-term weather forecasting and watching for severe weather such as thunderstorms , tornadoes , winter storms , precipitation types, etc. Geologists use specialized ground-penetrating radars to map the composition of Earth's crust . Police forces use radar guns to monitor vehicle speeds on the roads. Automotive radars are used for adaptive cruise control and emergency breaking on vehicles by ignoring stationary roadside objects that could cause incorrect brake application and instead measuring moving objects to prevent collision with other vehicles. As part of Intelligent Transport Systems , fixed-position stopped vehicle detection (SVD) radars are mounted on
10962-511: The project was about. Government officials began to view the development of atomic bombs in time to affect the outcome of the war as a genuine possibility. Vannevar Bush , the director of the OSRD, which was overseeing the project, visited Berkeley in February 1942, and found the atmosphere there "stimulating" and "refreshing". On 9 March 1942, he reported to the president, Franklin D. Roosevelt , that it might be possible to produce enough material for
11088-432: The radial component of the velocity is relevant. When the reflector is moving at right angle to the radar beam, it has no relative velocity. Objects moving parallel to the radar beam produce the maximum Doppler frequency shift. When the transmit frequency ( F T {\displaystyle F_{T}} ) is pulsed, using a pulse repeat frequency of F R {\displaystyle F_{R}} ,
11214-414: The response. Given all required funding and development support, the team produced working radar systems in 1935 and began deployment. By 1936, the first five Chain Home (CH) systems were operational and by 1940 stretched across the entire UK including Northern Ireland. Even by standards of the era, CH was crude; instead of broadcasting and receiving from an aimed antenna, CH broadcast a signal floodlighting
11340-410: The resulting frequency spectrum will contain harmonic frequencies above and below F T {\displaystyle F_{T}} with a distance of F R {\displaystyle F_{R}} . As a result, the Doppler measurement is only non-ambiguous if the Doppler frequency shift is less than half of F R {\displaystyle F_{R}} , called
11466-427: The roadside to detect stranded vehicles, obstructions and debris by inverting the automotive radar approach and ignoring moving objects. Smaller radar systems are used to detect human movement . Examples are breathing pattern detection for sleep monitoring and hand and finger gesture detection for computer interaction. Automatic door opening, light activation and intruder sensing are also common. A radar system has
11592-407: The scattered energy back toward the source. The extent to which an object reflects or scatters radio waves is called its radar cross-section . The power P r returning to the receiving antenna is given by the equation: where In the common case where the transmitter and the receiver are at the same location, R t = R r and the term R t ² R r ² can be replaced by R , where R
11718-431: The separation factor of any uranium enrichment process needs to be higher than 125 to produce 90% uranium-235 from natural uranium. The Maud Committee had recommended that this be done by a process of gaseous diffusion , but Oliphant had pioneered another technique in 1934: electromagnetic separation. This was the process that Nier had used. The principle of electromagnetic separation is that charged ions are deflected by
11844-416: The shape of a racetrack; hence the name. The two Alpha I buildings, 9201-1 and 9201-2, each contained two racetracks, with only one in the Alpha I 1 ⁄ 2 , 9201-3. The Beta racetracks were smaller, linear in shape, and optimized for recovery rather than production, with only 36 instead of 96 process bins. The four Alpha II racetracks were also linear in configuration. They incorporated many improvements,
11970-416: The site. It is a radiodetermination method used to detect and track aircraft , ships , spacecraft , guided missiles , motor vehicles , map weather formations , and terrain . A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna , a receiving antenna (often the same antenna is used for transmitting and receiving) and
12096-491: The target. If the wavelength is much shorter than the target's size, the wave will bounce off in a way similar to the way light is reflected by a mirror . If the wavelength is much longer than the size of the target, the target may not be visible because of poor reflection. Low-frequency radar technology is dependent on resonances for detection, but not identification, of targets. This is described by Rayleigh scattering , an effect that creates Earth's blue sky and red sunsets. When
12222-645: The technique allowed it to generate a 1,400 μA beam. That month, 75 μg samples enriched to 30% were shipped to the British and the Metallurgical Laboratory in Chicago. Other researchers also investigated electromagnetic isotope separation. At Princeton University , a group led by Henry D. Smyth and Robert R. Wilson developed a device known as an isotron. Using a klystron , they were able to separate isotopes using high-voltage electricity rather than magnetism. Work continued until February 1943, when, in view of
12348-519: The technology with the U.S. during the 1940 Tizard Mission . In April 1940, Popular Science showed an example of a radar unit using the Watson-Watt patent in an article on air defence. Also, in late 1941 Popular Mechanics had an article in which a U.S. scientist speculated about the British early warning system on the English east coast and came close to what it was and how it worked. Watson-Watt
12474-399: The third and first Alpha racetracks, now repaired, became operational in March 1944, and the fourth Alpha racetrack in April 1944. A third building, 9201-3, contained a fifth racetrack that incorporated some modifications, and was known as Alpha I 1 ⁄ 2 . This became operational on 3 June 1944. Work on the Alpha and Beta chemistry buildings, 9202 and 9203, commenced in February 1943, and
12600-560: The time the program was discovered, Iraq was estimated to be two or three years away from producing enough material for nuclear weapons. The program was destroyed in the Gulf War. Consequently, the Nuclear Suppliers Group added the electromagnetic separation equipment to its guidelines for transfers of nuclear-related dual-use equipment, material and technology. Mass spectrometer Too Many Requests If you report this error to
12726-403: The top and bottom of the vacuum tank. The effect of the shims was to slightly increase the magnetic field in such a way as to help focus the ion beam. Work would continue on the shims through 1943. The main calutron patents were Methods of and apparatus for separating materials (Lawrence), Magnetic shims (Oppenheimer and Frankel), and Calutron system (Lawrence). Burhop and Bohm later studied
12852-476: The trainees were not informed of the purpose of the equipment they were taught to operate. The calutrons were initially operated by scientists from Berkeley to remove bugs and achieve a reasonable operating rate. Then the Tennessee Eastman operators took over. Nichols compared unit production data, and pointed out to Lawrence that the young "hillbilly" girl operators were outproducing his Ph.Ds. They agreed to
12978-879: The transmitter. The reflected radar signals captured by the receiving antenna are usually very weak. They can be strengthened by electronic amplifiers . More sophisticated methods of signal processing are also used in order to recover useful radar signals. The weak absorption of radio waves by the medium through which they pass is what enables radar sets to detect objects at relatively long ranges—ranges at which other electromagnetic wavelengths, such as visible light , infrared light , and ultraviolet light , are too strongly attenuated. Weather phenomena, such as fog, clouds, rain, falling snow, and sleet, that block visible light are usually transparent to radio waves. Certain radio frequencies that are absorbed or scattered by water vapour, raindrops, or atmospheric gases (especially oxygen) are avoided when designing radars, except when their detection
13104-487: The two length scales are comparable, there may be resonances . Early radars used very long wavelengths that were larger than the targets and thus received a vague signal, whereas many modern systems use shorter wavelengths (a few centimetres or less) that can image objects as small as a loaf of bread. Short radio waves reflect from curves and corners in a way similar to glint from a rounded piece of glass. The most reflective targets for short wavelengths have 90° angles between
13230-467: The use of radar altimeters possible in certain cases. The radar signals that are reflected back towards the radar receiver are the desirable ones that make radar detection work. If the object is moving either toward or away from the transmitter, there will be a slight change in the frequency of the radio waves due to the Doppler effect . Radar receivers are usually, but not always, in the same location as
13356-564: The vacuum chamber. In February 1942, their team was consolidated with Lawrence's in Berkeley. While the process had been demonstrated to work, considerable effort was still required before a prototype could be tested in the field. Lawrence assembled a team of physicists to tackle the problems, including David Bohm , Edward Condon , Donald Cooksey , A. Theodore Forrester, Irving Langmuir , Kenneth Ross MacKenzie , Frank Oppenheimer , J. Robert Oppenheimer , William E. Parkins, Bernard Peters and Joseph Slepian . In November 1943 they were joined by
13482-587: Was $ 673 million (equivalent to $ 10.5 billion in 2023). The workforce at Y-12 dropped from a wartime peak of 22,482 on 21 August 1945 to less than 1,700 in 1949. All the calutrons were removed and dismantled, except for the XAX and XBX training tracks in Building 9731, and the Beta 3 racetracks in Building 9204–3. In 1947, Eugene Wigner , the director of the Oak Ridge National Laboratory (ORNL), asked
13608-608: Was a 1938 Bell Lab unit on some United Air Lines aircraft. Aircraft can land in fog at airports equipped with radar-assisted ground-controlled approach systems in which the plane's position is observed on precision approach radar screens by operators who thereby give radio landing instructions to the pilot, maintaining the aircraft on a defined approach path to the runway. Military fighter aircraft are usually fitted with air-to-air targeting radars, to detect and target enemy aircraft. In addition, larger specialized military aircraft carry powerful airborne radars to observe air traffic over
13734-545: Was a young woman, a recent graduate of a local high school. Training was initially conducted at the University of Tennessee . Training switched to Berkeley from April to September 1943, where it was conducted on the XA calutron and a 1:16 scale model of the Alpha racetrack, and then to Oak Ridge when the XAX calutron became available. Some 2,500 operators would be required once all the Alpha II calutrons were available. The Tennessee Eastman payroll at Y-12 ballooned from 10,000 in mid-1944 to 22,482 in August 1945. For security reasons,
13860-423: Was authorized on 2 April 1945 and was completed by 1 December 1945. A new group of Alpha chemistry buildings known as the 9207 group was commenced in June 1944, but work was halted in June 1945 before they were completed. Along with these main buildings, there were offices, workshops, warehouses and other structures. There were two steam plants for heating, and a power plant for electricity. The Alpha racetracks were
13986-444: Was carried out in 1946 with a calutron using a magnet taken from Germany. A site was chosen for an electromagnetic plant at Sverdlovsk-45 in 1946. The pilot plant, known as Plant 418, was completed in 1948. A more efficient design was developed in which the particle beams were bent by 225° instead of 180° as in the American calutron. It was used to complete the uranium enrichment process after technical difficulties were encountered with
14112-476: Was completed in September. Work on the Beta process building, 9204-1, began in May 1943, and was ready for operation on 13 March 1944, but was not completed until September 1944. Groves authorized Alpha II in September 1943. This consisted of two new Alpha process buildings, 9201-4 and 9201-5, another Beta, 9204-2, an extension to the Alpha chemistry building, and a new Beta chemistry building, 9206. When 9206 opened,
14238-459: Was correct. Leo Szilard and Walter Zinn soon confirmed that more than one neutron was released per fission, which made it almost certain that a nuclear chain reaction could be initiated, and therefore that the development of an atomic bomb was a theoretical possibility. There were fears that a German atomic bomb project would develop one first, especially among scientists who were refugees from Nazi Germany and other fascist countries. At
14364-467: Was dismantled on 24 November 1941, and its magnet used to create the first calutron. Its name came from Cal ifornia U niversity and cyclo tron . The work was initially funded by the Radiation Laboratory from its own resources, with a $ 5,000 grant from the Research Corporation . In December Lawrence received a $ 400,000 grant from the S-1 Uranium Committee. The calutron consisted of an ion source, in
14490-623: Was in desperately short supply. However, they realized that silver could be substituted, in an 11:10 ratio of copper:silver. On 3 August 1942, Nichols met with the Under Secretary of the Treasury , Daniel W. Bell , and asked for the transfer of silver bullion from the West Point Bullion Depository . Nichols later recalled the conversation: He explained the procedure for transferring the silver and asked, "How much do you need?" I replied, "Six thousand tons." 'How many troy ounces
14616-466: Was in the form of uranium hexafluoride ( UF 6 ). It was converted to uranium trioxide, which then went into the usual process for conversion to uranium tetrachloride. On 5 August 1945, K-25 started producing feed enriched to 23 percent, enough to be fed straight into the Beta racetracks. The remaining Alpha product was then fed into K-25. By September 1945, the calutrons had produced 88 kilograms of product with an average enrichment of 84.5 percent, and
14742-403: Was lost. In May 1970, the last 67 short tons (61 tonnes; 2,000,000 troy ounces) of silver was replaced with copper and returned to the Treasury. The XAX racetrack with two tanks and three coils was ready to train workers in August 1943. Bugs were discovered, but were not aggressively followed up. The first Alpha process building, 9201-1, was completed on 1 November 1943. When the first racetrack
14868-406: Was made on 11 May 1944. On 7 June 1944, Y-12 made its first delivery of weapons-grade Beta product, enriched to as high as 89% uranium-235. A major problem was that of loss of feed material and product. Only 1 part in 5,825 of the feed material became finished product. About 90 percent was splattered over the feed bottles or vacuum tanks. The problem was particularly acute with the enriched feed of
14994-748: Was sent to the U.S. in 1941 to advise on air defense after Japan's attack on Pearl Harbor . Alfred Lee Loomis organized the secret MIT Radiation Laboratory at Massachusetts Institute of Technology , Cambridge, Massachusetts which developed microwave radar technology in the years 1941–45. Later, in 1943, Page greatly improved radar with the monopulse technique that was used for many years in most radar applications. The war precipitated research to find better resolution, more portability, and more features for radar, including small, lightweight sets to equip night fighters ( aircraft interception radar ) and maritime patrol aircraft ( air-to-surface-vessel radar ), and complementary navigation systems like Oboe used by
15120-420: Was started up for testing on schedule in November, the 14-ton vacuum tanks crept out of alignment by as much as 3 inches (8 cm) because of the power of the magnets and had to be fastened more securely. A more serious problem arose when the magnetic coils started shorting out. In December Groves ordered a magnet broken open, and handfuls of rust were found inside. Moisture was also a problem in its own right, as
15246-432: Was that the beams interfered with each other, producing a series of oscillations called hash. An arrangement was devised that minimized the interference, resulting in reasonably good beams being produced, in September 1942. Robert Oppenheimer and Stan Frankel invented the magnetic shim , a device used to adjust the homogeneity of a magnetic field. These were sheets of iron about 3 feet (1 m) in width that were bolted to
15372-411: Was the first to use radio waves to detect "the presence of distant metallic objects". In 1904, he demonstrated the feasibility of detecting a ship in dense fog, but not its distance from the transmitter. He obtained a patent for his detection device in April 1904 and later a patent for a related amendment for estimating the distance to the ship. He also obtained a British patent on 23 September 1904 for
15498-574: Was the winding of the wire, which was too tight. Groves ordered the racetracks to be torn down and the magnets sent back to the factory to be cleaned and rewound. Rigid standards for preparation and cleanliness were instituted to prevent a recurrence of these problems. Training for the Beta tracks shifted from the XAX to the XBX training and development racetrack in November 1943. A second Alpha I racetrack became operational in January 1944. The first Beta racetrack and
15624-422: Was then reacted with carbon tetrachloride ( CCl 4 ) to produce uranium tetrachloride. Charles A. Kraus proposed a better method for large-scale production that involved reacting the uranium oxide with carbon tetrachloride at high temperature and pressure. This produced uranium pentachloride ( UCl 5 ) and phosgene ( COCl 2 ). While nowhere near as nasty as the uranium hexafluoride used by
15750-465: Was used to produce plutonium for India's first nuclear test on 18 May 1974. After the 1990–91 Gulf War , UNSCOM determined that Iraq had been pursuing a calutron program to enrich uranium. Iraq chose to develop the electromagnetic process over more modern, economic, and efficient methods of enrichment because calutrons were easier to build, with fewer technical challenges, and the components required to build them were not subject to export controls. At
15876-466: Was within an order of magnitude of 10 kg, which was small enough to be carried by a bomber of the day. The British Maud Committee then unanimously recommended pursuing the development of an atomic bomb. Britain had offered to give the United States access to its scientific research, so the Tizard Mission 's John Cockcroft briefed American scientists on British developments. He discovered that
#795204