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65-412: Construction of the observatory began in 1975, and in 1977 it became the second attached institution with ICRR. Its accomplishments include the observation of a super high energy cosmic ray air shower in 1995 that was previously thought to be impossible. This article about a Japanese building- or structure-related topic is a stub . You can help Misplaced Pages by expanding it . This article about

130-521: A 460 m {\displaystyle 460\,{\text{m}}} diameter circular array. The results of the experiment on the arrival directions of cosmic rays, however, where inconclusive. The Volcano Ranch experiment, which was built in 1959 and operated by John Linsley , was the first surface detector array of sufficient size to detect ultrahigh-energy cosmic rays . In 1962, the first cosmic ray with an energy of 10 20 eV {\displaystyle 10^{20}\,{\text{eV}}}

195-799: A saddle connecting two major 4000ers of the Bernese Alps : the Jungfrau and the Mönch . It lies at an elevation of 3,463 metres (11,362 ft) above sea level and is directly overlooked by the rocky prominence of the Sphinx . The Jungfraujoch is a glacier saddle, on the upper snows of the Aletsch Glacier , and part of the Jungfrau-Aletsch area , situated on the boundary between the cantons of Bern and Valais , halfway between Interlaken and Fiesch . Since 1912,

260-1122: A fast rise in the number of particles, before the average energy of the particles falls below ϵ c γ {\displaystyle \epsilon _{\text{c}}^{\gamma }} around the shower maximum, and a slow decay afterwards. Mathematically the profile can be well described by a slanted Gaussian, the Gaisser-Hillas function or the generalized Greisen function, N ( t ) = ϵ β e ( ( t − t 1 ) − 3 2 ln ⁡ s ) . {\displaystyle N(t)={\frac {\epsilon }{\sqrt {\beta }}}\,{\text{e}}^{\left((t-t_{1})-{\tfrac {3}{2}}\ln s\right)}.} Here β = ln ⁡ ( E 0 / ϵ c γ ) {\displaystyle \beta =\ln(E_{0}/\epsilon _{\text{c}}^{\gamma })} and t = X / X 0 {\displaystyle t=X/X_{0}} using

325-409: A fluorescence telescope at its maximum. For idealized electromagnetic showers, the angular and lateral distribution functions for electromagnetic particles have been derived by Japanese physicists Nishimura and Kamata. For a shower of age s {\displaystyle s} , the density of electromagnetic particles as a function of the distance r {\displaystyle r} to

390-449: A great wall of ice, whose projecting cornice of snow was fringed by long icicles, had to be avoided bearing left in the direction of the Mönch, along the base of the wall by a slippery pathway of ice formed from the dripping from the icicles above. At a point where the pathway thinned out nearly to a point, and was cut across by a transverse crevasse , the wall became low enough to be scaled by

455-596: A pass existed between Grindelwald and Fiesch in Valais in the late medieval period, later lost to the advancing glaciers. With the early development of tourism in Switzerland and the exploration of the High Alps in the 19th century, there were once again attempts to traverse the great ridge that encloses the head of the Aletsch Glacier , and connecting Fiesch with Grindelwald and Wengernalp . Four such routes were found, with

520-462: A plateau. This halting place was reached in about three hours. Above the bergschrund was a second and smaller plateau which was situated immediately under the long slopes of broken neve that lay below the saddle. The final and very arduous stage in the ascent was a single patch of dark rocks jutted out from the snow in the ridge connecting the Jungfrau with the Mönch. After more than an hour of climbing,

585-524: A post office. Several tunnels lead outside, where secured hiking trails on the crevassed glacier can be followed, in particular to the Mönchsjoch Hut . The normal route to the Jungfrau and Mönch starts from there. The Sphinx Observatory , one of the highest astronomical observatories in the world , provides an additional viewing platform at a height of 3,572 metres (11,719 ft), the second-highest in Switzerland . It can be reached by an elevator from

650-410: A significantly increased amount of muons, can be well approximated by a superposition of NKG-like functions, in which different particle components are described using effective values for s {\displaystyle s} and r M {\displaystyle r_{\text{M}}} . The original particle arrives with high energy and hence a velocity near the speed of light , so

715-432: A specific observatory, telescope or astronomical instrument is a stub . You can help Misplaced Pages by expanding it . Air shower (physics) Air showers are extensive cascades of subatomic particles and ionized nuclei, produced in the atmosphere when a primary cosmic ray enters the atmosphere. Particles of cosmic radiation can be protons , nuclei , electrons , photons , or (rarely) positrons . Upon entering

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780-508: A third was centered underneath with additional shielding. From the detection of air-shower particles passing through the Geiger counters in coincidence, he assumed that secondary particles are being produced by cosmic rays in the first shielding layer as well as in the rooftop of the laboratory, unknowing that the particles he measured were muons , which are produced in air showers and which would only be discovered three years later. He also noted that

845-590: A total of ( N ch ) n c = ( E 0 / ϵ c π ) β {\displaystyle (N_{\text{ch}})^{n_{\text{c}}}=(E_{0}/\epsilon _{\text{c}}^{\pi })^{\beta }} muons are produced, with β = ln ⁡ N ch / ln ⁡ ( 3 N ch / 2 ) ≃ 0.95 {\displaystyle \beta =\ln N_{\text{ch}}/\ln(3N_{\text{ch}}/2)\simeq 0.95} . The electromagnetic part of

910-446: Is a dimensionless constant. The shower age parameter s {\displaystyle s} is introduced to compare showers with different starting depths and different primary energies to highlight their universal features, as for example at the shower maximum s = 1 {\displaystyle s=1} . For a shower with a first interaction at t 0 = 0 {\displaystyle t_{0}=0} ,

975-524: Is a snow saddle located directly between the summits of Mathildespitze (west) and Sphinx (east). It is, however, most notably the lowest point between the Jungfrau and the Mönch , respectively third and fourth highest mountains in the Bernese Alps, and the key col of the former. The south side (canton of Valais), almost flat, is constituted by the Jungfraufirn, one of the branches of the Aletsch Glacier ,

1040-521: Is about 7 kilometers (4.3 mi) long, with gradients of up to 25%. The journey from Kleine Scheidegg to Jungfraujoch takes approximately 50 minutes including the stops at Eigerwand and Eismeer; the downhill return journey taking only 35 minutes. The Jungfraujoch complex plays an important role in John Christopher 's The Tripods novels. Located above the permanent snow line , the Jungfraujoch

1105-412: Is assumed to be the depth of the first interaction of the cosmic ray in the atmosphere. This approximation is, however, not accurate for all types of primary particles. Especially showers from heavy nuclei will reach their maximum much earlier. The number of particles present in an air shower is approximately proportional to the calorimetric energy deposit of the shower. The energy deposit as a function of

1170-431: Is most likely derived from the name Jungfrauenberg given to Wengernalp , so named for the nuns of Interlaken Monastery , its historical owner. However, the "virgin" peak was heavily romanticized as a "goddess" or "priestess" only in late 18th- to 19th-century Romanticism. After the first ascent in 1811 by Swiss alpinist Johann Rudolf Meyer, the peak was jokingly referred to as Mme Meyer (Mrs. Meyer). The Jungfraujoch

1235-412: Is officially the coldest place in Switzerland, although other higher locations with no weather station, for example the top of the nearby Jungfrau and Finsteraarhorn , probably experience a more extreme climate. According to Köppen climate classification , the Jungfraujoch has an alpine climate on the border between tundra climate (ET) and ice cap climate (EF) with long, cold winters lasting most of

1300-457: Is therefore publicly referred to as the Oh-My-God particle . The air shower is formed by interaction of the primary cosmic ray with the atmosphere, and then by subsequent interaction of the secondary particles, and so on. Depending on the type of the primary particle, the shower particles will be created mostly by hadronic or electromagnetic interactions. Shortly after entering the atmosphere,

1365-551: The Manhattan project . In the 1950s, the lateral and angular structure of electromagnetic particles in air showers were calculated by Japanese scientists Koichi Kamata and Jun Nishimura. In 1955, the first surface detector array to detect air showers with sufficient precision to detect the arrival direction of the primary cosmic rays was built at the Agassiz station at MIT . The Agassiz array consisted of 16 plastic scintillators arranged in

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1430-838: The Sphinx Observatory , are on the Valais side of the border, therefore in the municipality of Fieschertal. The ridge between the Jungfrau and the Mönch is a major European watershed as well. The north side is drained by the Weisse Lütschine , the Aare and the Rhine . The south side is drained by the Massa and the Rhone . There is a tradition in the Bernese Oberland, supported by some documentary evidence, that

1495-535: The invisible energy of the shower. Qualitatively, the particle content of a shower can be described by a simplified model, in which all particles partaking in any interaction of the shower will equally share the available energy. One can assume that in each hadronic interaction, 2 N ch {\displaystyle 2N_{\text{ch}}} charged pions and N ch {\displaystyle N_{\text{ch}}} neutral pions are produced. The neutral pions will decay into photons, which fuel

1560-402: The 14th century (Grimm, Deutsches Wörterbuch "bereits im 14. jahrh. als ortsname: des gotzhus zwing und ban vahet an Rotenhalden und denne die roten bachtalen uf unz an den grat, und den grat obnan hin ob Grüblen hin iemerme, unz an Joch. und ab Joch unz an Stoerben. weisth. 1, 4 (Zürich)"). The name Jungfrau ('Virgin'), which refers to the highest mountain overlooking the Jungfraujoch,

1625-565: The Argentinean desert. In 1933, shortly after the discovery of cosmic radiation by Victor Hess , Bruno Rossi conducted an experiment in the Institute of Physics in Florence, using shielded Geiger counters to confirm the penetrating character of the cosmic radiation. He used different arrangements of Geiger counters, including a setup of three counters, where two were placed next to each other and

1690-739: The Jungfraujoch and the Eigerjoch being among the most difficult passes in the Alps, despite the former having a relatively easy southern approach on the Aletsch Glacier. The first ascent of the north side of the Jungfraujoch succeeded in July 1862, by a party of six English climbers and six Swiss guides: Leslie Stephen , F. J. Hardy, H. B. George , Living, Moore, and Henry Morgan , with Christian Almer , Christian and Peter Michel, Ulrich Kauffmann, P. Baumann, and C. Bohren as guides. The time of ascent from Wengernalp

1755-676: The Jungfraujoch has been accessible to tourists by the Jungfrau line , a railway from Interlaken and Kleine Scheidegg , running partly underground through a tunnel through the Eiger and Mönch. The Jungfraujoch railway station , at an elevation of 3,454 metres (11,332 ft) is the highest in Europe . It lies east of the saddle, below the Sphinx station, and is connected to the Top of Europe building, which includes several panoramic restaurants, shops, exhibitions, and

1820-543: The Jungfraujoch is through the 7 kilometre-long tunnel of the Jungfrau Railway , accessed via Kleine Scheidegg on the north side, the railway pass between Lauterbrunnen and Grindelwald . Administrativelly, the Jungfraujoch is split between the territories of the municipalities of Lauterbrunnen and Fieschertal . Nearly all built infrastructure, including the Jungfraujoch railway station , Top of Europe complex and

1885-509: The Jungfraujoch. The observatory houses one of the Global Atmosphere Watch 's atmospheric research stations. The Jungfraujoch radio relay station , which is not accessible to the public, is installed west of the Jungfraujoch, on the Jungfrau ridge. It is Europe's highest radio relay station. The Swiss- and Austro-Bavarian-German term Joch means "saddle", in this case referring to the ridge between two higher peaks, as recorded in

1950-438: The atmosphere can be detected with surface detector arrays and optical telescopes. Surface detectors typically use Cherenkov detectors or scintillation counters to detect the charged secondary particles at ground level. The telescopes used to measure the fluorescence and Cherenkov light use large mirrors to focus the light on PMT clusters. Finally, air showers emit radio waves due to the deflection of electrons and positrons by

2015-449: The atmosphere, and conducted experiments using shielded scintillators and Wilson chambers on the Jungfraujoch at an altitude of 3500 m {\displaystyle 3500\,{\text{m}}} above sea level, and on Pic du Midi at an altitude of 2900 m {\displaystyle 2900\,{\text{m}}} above sea level, and at sea level. They found that the rate of coincidences reduces with increasing distance of

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2080-595: The atmosphere, initiating a cascade of secondary interactions that produce extensive showers of subatomic particles. The most important experiments detecting extensive air showers today are HAWC , LHAASO , the Telescope Array Project and the Pierre Auger Observatory . The latter is the largest observatory for cosmic rays ever built, operating with 4 fluorescence detector buildings and 1600 surface detector stations spanning an area of 3,000 km in

2145-431: The atmosphere, they interact with molecules and initiate a particle cascade that lasts for several generations, until the energy of the primary particle is fully converted. If the primary particle is a hadron, mostly light mesons like pions and kaons are produced in the first interactions, which then fuel a hadronic shower component that produces shower particles mostly through pion decay. Primary photons and electrons, on

2210-578: The atmosphere. Because ϵ c γ ≪ ϵ c π {\displaystyle \epsilon _{\text{c}}^{\gamma }\ll \epsilon _{\text{c}}^{\pi }} , the electromagnetic particles dominate the number of particles in the shower by far. A good approximation for the number of (electromagnetic) particles produced in a shower is N ≃ E 0 / GeV {\displaystyle N\simeq E_{0}/{\text{GeV}}} . Assuming each electromagnetic interaction occurs after

2275-575: The average radiation length X 0 ≃ 37 g / cm 2 {\displaystyle X_{0}\simeq 37\,{\text{g}}/{\text{cm}}^{2}} , the shower will reach its maximum at a depth of approximately X max ≃ X 1 + X 0 ln ⁡ ( E 0 GeV ) {\displaystyle X_{\text{max}}\simeq X_{1}+X_{0}\ln \left({\frac {E_{0}}{\text{GeV}}}\right)} , where X 1 {\displaystyle X_{1}}

2340-538: The cascade develops in parallel by bremsstrahlung and pair production. For the sake of simplicity, photons, electrons, and positrons are often treated as equivalent particles in the shower. The electromagnetic cascade continues, until the particles reach a critical energy of ϵ c γ ≃ 87 MeV {\displaystyle \epsilon _{\text{c}}^{\gamma }\simeq 87\,{\text{MeV}}} , from which on they start losing most of their energy due to scattering with molecules in

2405-452: The coincidence rate drops significantly for cosmic rays that are detected at a zenith angle below 60 ∘ {\displaystyle 60^{\circ }} . A similar experiment was conducted in 1936 by Hilgert and Bothe in Heidelberg . In a publication in 1939, Pierre Auger , together with three colleagues, suggested that secondary particles are created by cosmic rays in

2470-455: The cosmic ray was detected by the Fly's Eye fluorescence detector system and was estimated to contain approximately 240 billion particles at its maximum. This corresponds to a primary energy for the cosmic ray of about 3.2 × 10 20 eV {\displaystyle 3.2\times 10^{20}{\text{eV}}} . To this day, no single particle with a larger energy was recorded. It

2535-446: The detectors, but does not vanish, even at high altitudes. Thus confirming that cosmic rays produce air showers of secondary particles in the atmosphere. They estimated that the primary particles of this phenomenon must have energies of up to 10 15 eV = 1 PeV {\displaystyle 10^{15}\,{\text{eV}}=1\,{\text{PeV}}} . Based on the idea of quantum theory, theoretical work on air showers

2600-480: The electromagnetic component of the shower. Charged pions, π ± {\displaystyle \pi ^{\pm }} , preferentially decay into muons and (anti) neutrinos via the weak interaction . The same holds true for charged and neutral kaons. In addition, kaons also produce pions. Neutrinos from pion and kaon decay are usually not accounted for as parts of the shower because of their very low cross-section, and are referred to as part of

2665-499: The electromagnetic part of the shower. The charged pions will then continue to interact hadronically. After n {\displaystyle n} interactions, the share of the primary energy E 0 {\displaystyle E_{0}} deposited in the hadronic component is given by E π = ( 2 3 ) n E 0 {\displaystyle E_{\pi }=\left({\frac {2}{3}}\right)^{n}E_{0}} , and

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2730-575: The electromagnetic part thus approximately carries E γ = ( 1 − ( 2 3 ) n ) E 0 {\displaystyle E_{\gamma }=\left(1-\left({\frac {2}{3}}\right)^{n}\right)E_{0}} . A pion in the n {\displaystyle n} th generation thus carries an energy of E 0 / ( 3 N ch / 2 ) n {\displaystyle E_{0}/(3N_{\text{ch}}/2)^{n}} . The reaction continues, until

2795-403: The electromagnetic radiation length in air, X 0 = 37 g / cm − 2 {\displaystyle X_{0}=37\,{\text{g}}/{\text{cm}}^{-2}} . t 1 {\displaystyle t_{1}} marks the point of the first interaction, and ϵ ≈ 0.31 {\displaystyle \epsilon \approx 0.31}

2860-400: The geomagnetic field. As advantage over the optical techniques, radio detection is possible around the clock and not only during dark and clear nights. Thus, several modern experiments, e.g., TAIGA , LOFAR , or the Pierre Auger Observatory use radio antennas in addition to particle detectors and optical techniques. Jungfraujoch The Jungfraujoch ( German : lit. "maiden saddle") is

2925-453: The ladder. This was the last serious obstacle: a moderate slope of névé, unbroken by crevasses, then led up to the summit of the saddle. After reaching the first patch of rocks, a short way below the saddle on the south side, the party divided: George and Moore, with C. Almer and U. Kaufmann went down to the Eggishorn and Fiesch, therefore completing the first crossing of the Jungfraujoch, while

2990-507: The longest in the Alps . From the south, the Jungfraujoch can be relatively easily accessed by mountaineers in two days from the region of Fiesch , via the Konkordia Hut . The north side (canton of Bern) is almost vertical with a difference of height of nearly 3,000 metres from the bottom of the valley at Interlaken , with no easy natural access. For those reasons, the only easy and quick access to

3055-411: The number of particles N {\displaystyle N} , Molière radius r M {\displaystyle r_{\text{M}}} and the common Gamma function . N {\displaystyle N} can be given for example by the longitudinal profile function. The lateral distribution of hadronic showers (i.e. initiated by a primary hadron, such as a proton), which contain

3120-442: The number of radiation lengths t {\displaystyle t} . The longitudinal profiles of showers are particularly interesting in the context of measuring the total calorimetric energy deposit and the depth of the shower maximum, X max {\displaystyle X_{\text{max}}} , since the latter is an observable that is sensitive to type of the primary particle. The shower appears brightest in

3185-518: The other hand, produce mainly electromagnetic showers. Depending on the energy of the primary particle, the detectable size of the shower can reach several kilometers in diameter. The air shower phenomenon was unknowingly discovered by Bruno Rossi in 1933 in a laboratory experiment. In 1937 Pierre Auger , unaware of Rossi's earlier report, detected the same phenomenon and investigated it in some detail. He concluded that cosmic-ray particles are of extremely high energies and interact with nuclei high up in

3250-723: The pions reach a critical energy ϵ c π ≃ 20 GeV {\displaystyle \epsilon _{\text{c}}^{\pi }\simeq 20\,{\text{GeV}}} , at which they decay into muons. Thus, a total of n c = ⌈ ln ⁡ ( E 0 / ϵ c π ) ln ⁡ ( 3 2 N ch ) ⌉ {\displaystyle n_{\text{c}}=\left\lceil {\frac {\ln \left(E_{0}/\epsilon _{\text{c}}^{\pi }\right)}{\ln \left({\tfrac {3}{2}}\,N_{\text{ch}}\right)}}\right\rceil } interactions are expected and

3315-424: The primary cosmic ray (which is assumed to be a proton or nucleus in the following) is scattered by a nucleus in the atmosphere and creates a shower core - a region of high-energy hadrons that develops along the extended trajectory of the primary cosmic ray, until it is fully absorbed by either the atmosphere or the ground. The interaction and decay of particles in the shower core feeds the main particle components of

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3380-465: The products of the collisions tend also to move generally in the same direction as the primary, while to some extent spreading sidewise. In addition, the secondary particles produce a widespread flash of light in forward direction due to the Cherenkov effect , as well as fluorescence light that is emitted isotropically from the excitation of nitrogen molecules. The particle cascade and the light produced in

3445-519: The railway reached only to the height of the Jungfraujoch saddle, rather than the summit of the Sphinx, and had only two intermediate stations. However, even in its current state, the Jungfraubahn is a significant achievement in engineering and construction, still holding the title for highest railway in Europe. The train into the mountain leaves from Kleine Scheidegg , which can be reached by trains from Grindelwald and Lauterbrunnen . The train enters

3510-670: The remainder of the party returned to Grindelwald by the Mönchsjoch . Adolf Guyer-Zeller first thought of the idea of a tunnel in 1893, and at that point, he had planned to have seven stations inside the tunnel before reaching the peak of the Sphinx. The building of the tunnel started on July 27, 1896 and took 16 years to complete. The construction phase was troubled by many problems including monetary shortages, inclement weather and mounting deaths due to construction accidents. The worst accident occurred in 1908, when 30 tons of dynamite accidentally exploded. When construction finally finished,

3575-421: The shower age s {\displaystyle s} is usually defined as s = 3 t t + 2 β {\displaystyle s={\frac {3t}{t+2\beta }}} . The image shows the ideal longitudinal profile of showers using different primary energies, as a function of the surpassed atmospheric depth X {\displaystyle X} or, equivalently,

3640-800: The shower axis can be approximated by the NKG function ϱ ( r ) = N 2 π r M 2 Γ ( 9 2 ) Γ ( s ) Γ ( 9 2 − 2 s ) ( r r M ) s − 2 ( 1 + r r M ) s − 9 / 2 , {\displaystyle \varrho (r)={\frac {N}{2\pi r_{\text{M}}^{2}}}{\frac {\Gamma ({\tfrac {9}{2}})}{\Gamma (s)\Gamma ({\frac {9}{2}}-2s)}}\left({\frac {r}{r_{\text{M}}}}\right)^{s-2}\,\left(1+{\frac {r}{r_{\text{M}}}}\right)^{s-9/2},} using

3705-438: The shower, which are hadrons, muons, and purely electromagnetic particles. The hadronic part of the shower consists mostly of pions , and some heavier mesons , such as kaons and ϱ {\displaystyle \varrho } mesons. Neutral pions, π 0 {\displaystyle \pi ^{0}} , decay by the electroweak interaction into pairs of oppositely spinning photons, which fuel

3770-418: The structure functions derived by Kamata and Nishimura. A novel detection technique for extensive air showers was proposed by Greisen in 1965. He suggested to directly observe Cherenkov radiation of the shower particles, and fluorescence light produced by excited nitrogen molecules in the atmosphere. In this way, one would be able to measure the longitudinal development of a shower in the atmosphere. This method

3835-417: The surpassed atmospheric matter, as it can for example be seen by fluorescence detector telescopes, is known as the longitudinal profile of the shower. For the longitudinal profile of the shower, only the electromagnetic particles (electrons, positrons, and photons) are relevant, as they dominate the particle content and the contribution to the calorimetric energy deposit. The shower profile is characterized by

3900-485: The tunnel running eastward through the Eiger shortly after leaving Kleine Scheidegg. It runs close behind the Eiger's north face, stopping at Eigerwand, where there is a window about 8 m long and a metre high, halfway up the face. The windows have been placed in holes used to remove excavated rock from the tunnel during construction, and are also occasionally used as access points, by climbers, and also rescue parties. This window

3965-437: Was carried between 1935 and 1940 out by many well-known physicists of the time (including Bhabha , Oppenheimer , Landau , Rossi and others), assuming that in the vicinity of nuclear fields high-energy gamma rays will undergo pair-production of electrons and positrons, and electrons and positrons will produce gamma rays by radiation. Work on extensive air showers continued mainly after the war, as many key figures were involved in

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4030-438: Was first applied successfully and reported in 1977 at Volcano Ranch, using 67 optical modules. Volcano Ranch finished its operation shortly after due to lack of funding. Many air-shower experiments followed in the decades after, including KASCADE , AGASA , and HIRES . In 1995, the latter reported the detection of an ultrahigh-energy cosmic ray with an energy beyond the theoretically expected spectral cutoff. The air shower of

4095-484: Was nine hours. The party turned back on the first day at a bergschrund , returning on the following day with a ladder 25 ft (7.6 m) in length, carried by Peter Rubi, a porter from Grindelwald. The way lay at first by the rocky buttress of the Mönch , separating the Eiger and Guggi glaciers. From the buttress the route descended a short distance in order to reach the Guggi Glacier, which could be ascended to

4160-420: Was reported. With a footprint of several kilometers, the shower size at the ground was twice as large as any event recorded before, approximately producing 5 × 10 10 {\displaystyle 5\times 10^{10}} particles in the shower. Furthermore, it was confirmed that the lateral distribution of the particles detected at the ground matched Kenneth Greisen 's approximation of

4225-479: Was used for one of the final scenes of a Clint Eastwood spy movie , The Eiger Sanction . There one can get off the train to admire the view before the train continues five minutes later. The tunnel then turns west, heading towards the Jungfrau. There is a second stop at a window looking out on the Eismeer ("Sea of Ice") before the train continues to the Jungfraujoch. The tunnel was constructed between 1898 and 1912; it

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