| dbo:abstract
|
- The Big European Bubble Chamber (BEBC) is a large detector formerly used to study particle physics at CERN. The chamber body, a stainless-steel vessel, was filled with 35 cubic metres of superheated liquid hydrogen, liquid deuterium, or a neon-hydrogen mixture, whose sensitivity was regulated by means of a movable piston weighing 2 tons. The liquids at typical operation temperatures around 27 K were placed under overpressure of about 5 standard atmospheres (510 kPa). The piston expansion, synchronized with the charged particle beam crossing the chamber volume, caused a rapid pressure drop; in consequence the liquid reached its boiling point. During each expansion, charged particles ionized the atoms of the liquid as they passed through it and the energy deposited by them initiated boiling along their path, leaving trails of tiny bubbles. These tracks were photographed by the five cameras mounted on top of the chamber. The stereo photographs were subsequently scanned and all events finally evaluated by a team of scientists. After each expansion, the pressure was increased again to stop the boiling. The bubble chamber was then ready again for a new cycle of beam exposure. The conception and construction of giant bubble chambers such as Gargamelle and BEBC was based on know-how acquired through the construction and operation of smaller bubble chambers such as the 30 cm hydrogen chamber, which came into operation at CERN in 1960, and the 2 m hydrogen chamber four years later. The BEBC project was launched in 1966 by CERN, France (Saclay), and Germany (DESY) and installed at CERN in the early 1970s. The chamber body was surrounded by the then-largest superconducting solenoid magnet of two coils in a Helmholtz arrangement. The magnet coils were fabricated at CERN using copper-reinforced niobium–titanium superconductor cable. The BEBC coils created a strong magnetic field of 3.5 T over the sensitive volume of the chamber. Thus, the fast charged particles passing through the chamber were bent in the magnetic field, providing information on their momentum. The first images were recorded in 1973 when BEBC first received a beam from the Proton Synchrotron (PS). From 1977 to 1984, the chamber took photos in the West Area neutrino beam line of the Super Proton Synchrotron (SPS) and in hadron beams at energies of up to 450 GeV. During 1978, a Track-Sensitive Target (TST) was installed to combine the advantages of hydrogen and heavy liquid bubble chambers. Hydrogen-filled chambers enable the study of particle interactions with free protons but they have a low efficiency for gamma ray conversion. On the other hand, heavy liquid filling is better suited for the detection of gamma rays but the events are harder to interpret. An External Muon Identifier (EMI) and an External Particle Identifier (EPI) were added to the BEBC in 1979 to respectively identify muons and charged hadrons leaving the chamber. Furthermore, an Internal Picket Fence (IPF) was used to obtain timing signals for events occurring in the bubble chamber, helping to suppress the background. These changes transformed BEBC into a hybrid detector. The BEBC experiments were: , , , , , , , , , , , , , , , , , , , , , and . By the end of its active life in 1984, BEBC had delivered a total of 6.3 million photographs to 22 experiments. Around 600 scientists from some fifty laboratories throughout the world had taken part in analyzing the 3000 km of film it had produced. BEBC enabled the discovery of D-mesons and promoted the developments of neutrino and hadron physics, carrying out one of the richest physics programs. It is now on display at CERN's Microcosm Museum. (en)
- La Big European Bubble Chamber (BEBC) fu una camera a bolle utilizzata negli esperimenti di fisica delle particelle al CERN. Si tratta di un recipiente in acciaio inossidabile di 3.7 m di diametro e 4 m in altezza, che veniva riempito con 35 m3 di idrogeno liquido, deuterio molecolare (D2) o di una miscela idrogeno/neon. La pressione del liquido veniva regolata da un pistone di 2 tonnellate: dopo l'espansione, le particelle cariche lasciavano tracce di bolle nella traiettoria, poiché il liquido raggiungeva il punto di ebollizione. La BEBC era circondata da un magnete superconduttore che produceva un campo magnetico di 3.5 T. Il progetto della BEBC fu proposto nel 1966, la costruzione avvenne nel 1967 da parte di un team formato da membri dell'Università di Heildelberg, dall'École polytechnique e del CERN, l'installazione avvenne all'inizio degli anni '70. Nel 1973 entrò in funzione presso l'acceleratore Proton Synchrotron (PS). Dal 1977 al 1984 ha operato nella linea di fascio di neutrini del Super Proton Synchrotron (SPS), dove è stata esposta a fasci di neutrini e adroni con energie fino a 450 GeV. Durante la sua attività, la BEBC aveva prodotto un totale di 6,3 milioni di lastre fotografiche da parte di 22 esperimenti dedicati allo studio dei neutrini e alla fisica degli adroni. Circa 600 scienziati provenienti da una cinquantina di laboratori in tutto il mondo avevano preso parte al complesso lavoro di analisi dei 3000 km di pellicola fotografica prodotti. (it)
- BEBC do inglês Big European Bubble Chamber (Grande Câmara de Bolhas Europeia) foi construída dum consorcio entre a Alemanha (University of Heildelberg DESY), a França (Ecole Ploytechnique SACLAY) e o CERN e as primeiras fotografias foram tirada em 1973. A enorme massa desta câmara de bolhas tinha 3,7 m de diâmetro e 4 m de altura, estva cheia com 35 m3 de um líquido (hidrogénio, deutério ou uma mistura de néon-hidrogénio), cuja sensibilidade era regulada por pistão com 2 toneladas. Durante cada expansão, e devido à enorme diminuição da pressão dentro da câmara, a trajectória da partícula carregada eletricamente era assinalada por um traço de bolhas, nos locais onde o líquido atingia o pontos de ebulição devido à sua passagem. Os eventos eram captados numa película cinematográfica (filme) que era revelado para ser examinado e estudado posteriormente, ver pormenores em trackball (Cern). As primeiras imagens foram registrada em 1973 quando a BEBC, equipada com o maior íman supercondutor da época, e pela primeira vez, recebeu um feixe proveniente do Sincrotrão a Protões (PS), do CERN. Em 1977 foi exposta a feixes de neutrinos e hadrões a energias da ordem dos 450 GeV quando o Super Sincrotrão a Protões (SPS) entrou em funcionamento. No final da sua carreira 1984, tinha fornecido um total de 6,3 milhões de fotografias a 22 experiências dedicadas à física de neutrinos e hadrões. Cerca de 600 cientistas de cerca de quinze laboratórios dedicaram-se a analisar os cerca de 3 000 km de filme que ela havia produzido. (pt)
|
| rdfs:comment
|
- The Big European Bubble Chamber (BEBC) is a large detector formerly used to study particle physics at CERN. The chamber body, a stainless-steel vessel, was filled with 35 cubic metres of superheated liquid hydrogen, liquid deuterium, or a neon-hydrogen mixture, whose sensitivity was regulated by means of a movable piston weighing 2 tons. The liquids at typical operation temperatures around 27 K were placed under overpressure of about 5 standard atmospheres (510 kPa). The piston expansion, synchronized with the charged particle beam crossing the chamber volume, caused a rapid pressure drop; in consequence the liquid reached its boiling point. During each expansion, charged particles ionized the atoms of the liquid as they passed through it and the energy deposited by them initiated boiling (en)
- La Big European Bubble Chamber (BEBC) fu una camera a bolle utilizzata negli esperimenti di fisica delle particelle al CERN. Si tratta di un recipiente in acciaio inossidabile di 3.7 m di diametro e 4 m in altezza, che veniva riempito con 35 m3 di idrogeno liquido, deuterio molecolare (D2) o di una miscela idrogeno/neon. (it)
- BEBC do inglês Big European Bubble Chamber (Grande Câmara de Bolhas Europeia) foi construída dum consorcio entre a Alemanha (University of Heildelberg DESY), a França (Ecole Ploytechnique SACLAY) e o CERN e as primeiras fotografias foram tirada em 1973. No final da sua carreira 1984, tinha fornecido um total de 6,3 milhões de fotografias a 22 experiências dedicadas à física de neutrinos e hadrões. Cerca de 600 cientistas de cerca de quinze laboratórios dedicaram-se a analisar os cerca de 3 000 km de filme que ela havia produzido. (pt)
|
