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Measurements of cosmic ray particles in the energy range of 10 11 – 10 13 eV in the PAMELA experiment 21 st European Cosmic Ray Symposium, Ko š ice, Slovakia 9 - 12 September 2008 A.N. Kvashnin, on behalf of PAMELA collaboration
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Trk, Sign of charge, rigidity, dE/dx. Electron energy, dE/dx, lepton-hadron separation e-e- p - e+e+ p (He,…) Trigger, ToF, dE/dx + GF ~21.5 cmsr, Mass: 470 kg Size: 130x70x70 cm GF ~21.5 cm 2 sr, Mass: 470 kg Size: 130x70x70 cm 3 For the search of high energy particles in PAMELA experiment we have used the data from Tracker, CALO, and ND detectors
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We study high energy cosmic rays, namely, cosmic ray spectra of all particles, protons, helium nuclei, and electrons in the energy region of 10 11 – ~10 14 eV. Method: In this work data of the tracker (G = 21 cm 2 sr ) and calorimeter are utilized (G cal = 470 cm 2 sr).
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We calculated the expected number of events in the combination calorimeter + tracker per one year (G = 21 cm 2 sr) Energy, TeV > 0.1>1.0> 5> 10 Protons, interacted in 5 top layers (3.76 X-units) 229006164917 Electrons1000120.50.13
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Expected number of events per one year only in the calorimeter (G = 470 cm 2 sr) Energy, TeV > 0.1>1.0> 5> 10 Protons, interacted in 5 top layers (3.76 X-units) 512000138001100371 Electrons24000263113
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To approximate cascade in CALO we have used the following expression: N(x) = N m exp[- (x – x m ) 2 /(d(x + kx m ))], where d and k are parameters (C. Song for HIREs collaboration. Study of the longitudinal development of air shower with CORSICA. Proc. of ICRC, 2001, Hamburg, Germany, HE, 490-494).
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K = 0.85 d = (44.5 – 43.5) g/cm 2 This expression describes calculated cascade curves very well.
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k 1 = k 2 = 0.85 d 1 = (52 - 44) g/cm 2 d 2 = (60 - 44) g/cm 2 The special program was developed by our colleague Igor Nikitin to analyze longitudinal and transverse distribution of cascade particles.
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Q tot =138E 0 R 2 =0.72
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Thank you!
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electrons
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PAMELA collaboration Moscow St. Petersburg Russia: Sweden: KTH, Stockholm Germany: Siegen Italy: BariFlorenceFrascatiTriesteNaplesRome CNR, Florence
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Grigorov N.L., Cosmic Research, 1995, v. 33, p. 339 Дж. Адамс, Зацепин В.И. И др., Изв. АН, сер. Физ., 1997, т. 61, стр. 1181 ТУС Adams J., Zatsepin V.I. et al. Izv. RAS, ser. fiz., 1997, v. 61, p. 1181
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Proton spectrum Curves are approximations: J p (E)=A(0.1/E) 1.62 1/[1+(E/a) /2], where 1 – а = 1.5 TeV, = 0.7; 2 - а = 0.7 TeV, = 0.5;
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(dE/dt) = E 0 b[(bt) a-1 ]*exp(-bt)/Г(a), where t is the radiation length, E 0 is the total cascade energy, b and a are parameters, defined as [(a-1)/b] = ln (E o /E c ) + C, E c is critical energy, equal to 7.97 MeV, С = - 0.5 for a cascade from electron, С = 0.5 for a cascade from gamma ray, Г(a) is the gamma-function. (The European Physical Journal C15, 1-878 (2000); Review of Particle Physics).
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Каскадная кривая для протонов N(x) = N 1m exp[- (x – x 1m ) 2 /(d 1 (x + k 1 x 1m ))] + N 2m exp[- (x – x 2m ) 2 /(d 2 (x + k 2 x 2m ))], где d 1, d 2 и k 1, k 2 – параметры (C. Song for HIREs collaboration. Study of the longitudinal development of air shower with CORSICA. Proc. of ICRC, 2001, Hamburg, Germany, HE, 490-494).
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k = 0.83 d = 2 g/cm 2
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k = 0.83 d = 2 g/cm 2
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k = 0.83 d = 2 g/cm 2
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