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Radiation Policy for CALO electronics History: • Previous Montecarlo Calculations by V. Talanov I. Korolko=> about 100rads/year and about 10**9 neutrons/cm**2 per year >20 MeV • Test at the ORSAY 200MeV proton cyclotron • Calculation of effects on electronic (Machefert et al) (note 2002-21) • As a consequence since last year redesign of electronics to be SEU proof New Montecarlo calculation of radiation levels by L. Shektman using LHCb classic- and a safety factor of two for the flux => 200-300 rads per year typical We should understand the meaning of maximum=>* LHCb radiation hardness policy for electronics given by J.Christiansen (May 2002 electronic meeting in LHCb week) =>* 11 JULY 2002 1 Jacques Lefrancois Update on radiation levels on May 2002 by Lev Shekhtman 11 JULY 2002 2 Jacques Lefrancois LHCb front-end meeting on May 2002 by Joergen Christiansen 11 JULY 2002 3 Jacques Lefrancois Calorimeter policy •The Krad problem does not seem severe. •The SEU problem is handled by the use of ACTEL and triple voting for key registers. •The main remaining problem is SEL: it is very difficult to accumulate enough irradiation on a few chips in a proton beam to simulate 1000s of chips in LHCb neutron flux without exceeding the Krads limit =>* note LHCb 2002-021: • test with ions •Protect the cards and components by a resettable fuse 11 JULY 2002 4 Jacques Lefrancois FUSE = Polyswitch = polymer +carbon powder price 0.5 euro EX: 2.2 A normal state 0.2 volts drop, > 2.2A => large resistance limits current to < 1.1 A until reset of power supplies and cool down Q: is it rad hard? Is the 0.2 volts stable? If not is it creating problem in digital part? Is the protection good enough? Test with ions : SEU/SEL caused by recoil ions with large LET (6? to 15 MeV/mg) Largest LET produced by neutron (proton) interaction = 15 MeV/mg but the cross section is low. Testing with ions is more sensitive but computation is needed using neutron cross section. Test done with ions with LET of about 15 (58 MeV*A Krypton) Numbers for SEL life use assumption that SEL probability is flat between 6 and 15. This could be pessimistic 11 JULY 2002 5 Jacques Lefrancois Proton Irradiation at CPO Component Duration (s) Dose (krad) SEL equivalent (year) 1 3479 (~1h) 22.6 87 2 1643 (~1/2h) 10.7 41 3 1896(~1/2h) 12.3 47 4 1800 (~1/2h) 11.7 45 11 JULY 2002 6 Jacques Lefrancois Ion Irradiation at Ganil Component # SEL Cumul. Time (s) Surf max 95%CL Surf min 95%CL Psel(neutron) Resistance (year.chip-1) Shaper 0 16000 8.9x10-9 - <1.8x10-14 >14000 RAM 0 4000 3.9x10-8 - <7.8x10-14 >3205 Serial 215/216 2 2521 1.3x10-7 4.0x10-8 <2.6x10-13 >961 S. 215/216 Drv 9 1682 5.0x10-7 1.3x10-7 <10-12 >250 Serial 483/484 7 2254 3.1x10-7 5.7x10-8 <6.2x10-13 >403 S. 483/484 Drv 13 (13 ?) 8.1x10-5 (?) 2.7x10-5(?) 1.62x10-10(?) >1.5 (?) 11 JULY 2002 7 Jacques Lefrancois Recommended tests Idealy one should irradiate cards for a few 10**7 relativistic lead ions at the SPS. This tests all components and the most severe SEL and SEU conditions with about 20 Krads of TID. However the last SPS ion beam period is in autumn 2003 cards may not be ready. ALL components could instead be tested at Ganil or GSI or at a cyclotron proton beam CPO or Louvain However the use of protons may require many components to have enough statistics 11 JULY 2002 8 Jacques Lefrancois Components tested & to be tested Main components already tested • PS/SPD and ECAL/HCAL amplifier-integrator • Multiplexers (drivers and receivers) • Memories (32K 16bits) • Actels To be tested: • Other memories (L1 buffer +?) • Line drivers • Variable delay chip • Others??? (fuse+…) A common test is the only efficient procedure=> : when? 11 JULY 2002 9 Jacques Lefrancois