Yuri Arestov, IHEPPrague, April 17, GaAs:Cr for HEP – radiation tests IHEP, Protvino NCPHEP, Minsk SIPT, Tomsk ICBP, Puschino

Yuri Arestov, IHEPPrague, April 17, Our predecessors RD-20, CERN Si, GaAs RD-48, CERN Si, GaAs A. Vorobiev, IHEP GaAs, Si P. Sellin e al, 1995 GaAs neutrons, 1 MeV, fluence up to n/cm -2 A. Vorobiev, IHEP, 2002 GaAs cooling, temperature dependence FNAL, D0 report, 2002 Silicon detectors from ELMA, ST, Ham., … and many others

Yuri Arestov, IHEPPrague, April 17, Doping GaAs by Chromium – the 5-year practice of a new technology in Tomsk Resistive Si structures have not been obtained so far. World studies of GaAs irradiation tolerance related mainly to GaAs structures of the previous generation. A new unique production technology of resistive GaAs:Cr (doped by Chromium) belongs to Tomsk. As was earlier shown by estimates and by the first measurements (Protvino, RAL), GaAs:Cr radiation hardness can be higher than that of Si by a factor of 10 or larger. structure type SiGaAs p-i-n - -n YES NO YES

Yuri Arestov, IHEPPrague, April 17, GaAs pad 1cm 1cm Cigarette lighter General view

Yuri Arestov, IHEPPrague, April 17, GaAs:Cr general properties a – taken as for Ge with Z=32 and A=72.6 and =5.32 g/cm 3. b – calculated as E c = 610 MeV/(Z+1.24) c – calculated as R M = X 0 21 MeV/E c

Yuri Arestov, IHEPPrague, April 17, GaAs vs Si ! ! Properties (by courtesy of O.P. Tolbanov) Si GaAs:Cr Ionization density, dN/dx (pair/ m) Charge drift velocity, cm/sec Response (amplitude of induced current per mip), A Radiation hardness in terms of CCE, Charge Collection Efficiency 30% at ~10 12 cm -2 50% ~10 14 cm -2 Leakage currentRefrigeration needed No refrigeration

Yuri Arestov, IHEPPrague, April 17, GaAs test series in Nov – Jan Proton beam at IHEP booster Gamma source in Puschino Data analysis in Protvino and Tomsk

Yuri Arestov, IHEPPrague, April 17, Absorbed dose – is it known accurately? -- YES Direct measurement with Al foils -- Г.И. Бритвич Verification with booster beam profiles – А.С. Гуревич Mrad Fluence, p/cm**2 1.7· · ·10 15

Yuri Arestov, IHEPPrague, April 17, GaAs diodes NN= 1 7 Low beam intensity I p = p/pulse NOTE. Diode N3 was irradiated up 40 Mrad, and later it was found to be damaged mechanically due to an unknown reason. N3 0.4 Mrad Mrad 2 Mrad 3.5 Mrad 20 Mrad40 Mrad80 Mrad 120 Mrad VACs before /after

Yuri Arestov, IHEPPrague, April 17, Stand at work A.G. Kholodenko, Это сбор заряда от напряжения, просто данные и центры тяжести сигнального и пъедестального пиков.

Yuri Arestov, IHEPPrague, April 17, GaAs:Cr 1cm1cm detectors in 1.7 GeV/c proton beam (Dec. 2003) 14 GaAs detectors. were exposed, and 7 of them to low lintensity beam with p/pulse and 7 to high-intensity beam with p/pulse. The absorbed doses were the same in both sets and they corresponded to fluences from p/cm 2 to p/cm 2.

Yuri Arestov, IHEPPrague, April 17,

Yuri Arestov, IHEPPrague, April 17, GaAs N15 and N16 irradiated by gammas source: Co 27 60, E = 1.25 MeV Dose rate 96 Krad/hour Absorbed dose 5 Mrad NOTE. Unfortunately, no curves obtained before irradiation

Yuri Arestov, IHEPPrague, April 17, GaAs: Cr 1cm1cm detectors at gamma irradiation (Jan. 2004) The detectors were exposed to source with the gamma energy 1.25 MeV. The absorbed doses ranged from 5 to 51 Mrad. The figures show the full tolerance of GaAs to the gamma fluxes within this load range.

Yuri Arestov, IHEPPrague, April 17, Conclusion О.П. Толбанов говорит: Вывод 3: В GaAs вдвое выше плотность ионизации, втрое выше быстродействие и в 5 раз выше амплитуда импульсов наведённого тока. Вывод 4: GaAs в сравнении с Si имеет радиационную стойкость более, чем на 2 порядка выше. GaAs detectors provide: Stronger signal: Higher radiation hardness: Tolerant leakage currents (no refrigeration) New high-tech opportunities in HEP instrumentation Applied science and interdisciplinary studies

Yuri Arestov, IHEPPrague, April 17, We continue to work… We want To continue studies in hadron beams up to a conclusive step. To irradiate in neutron beams. To perform a direct comparison with Si in the same experiments. To involve interested parties. To get a support.