Attivit di irradiazione F Riggi INFN and Dept

Attività di irradiazione F. Riggi INFN and Dept. of Phys & Astronomy, Catania ITS Upgrade, incontro con i referee, 24 Giugno 2011

Past activities on radiation hardness of ALICE pixel sensors (1998 -2000) 2/12 ● Evaluation of expected dose in ALICE by GEANT simulations ● Irradiations with different probes: ● X-ray facility@CERN ● 15 Me. V electrons, S. Luigi Hospital, Catania (beam for medical applications) ● Thermal neutrons, ENEA@Casaccia (TAPIRO Research Nuclear Reactor) ● 14 Me. V neutrons, ENEA (Frascati) Neutron Generator ● 60 Co gammas, ISS Facility (Roma) ● 6. 5 Me. V protons, LNL Van De Graaff (Legnaro) ● Old references from past work: - NIM A 476(2002)765 - ALICE Int. Note ALICE/98 -43(1998) - ALICE Int. Note ALICE/99 -01(1999) - ALICE Int. Note ALICE/99 -31(1999) - ALICE Int. Note ALICE/00 -24(2000) - Talk at the 3 rd Int. Conference on Radiation Damage of Semiconductors, Detectors and Devices, Firenze, June 28 -30, 2000

3/12

4/12 Independent estimate according to old GEANT simulations A. Badalà et al. , ALICE Note INT-1999 -31 At r=2 cm expected dose around 1 Mrad Applying a safety factor of 2, envisaged dose 2 Mrad

5/12 On-going discussions during the last ITS Upgrade Meetings are pointing towards the possibility to arrive at a first irradiation of different samples of monolithic TPAC chips by the use of different probes (start from the CERN X-ray facility). ● Samples to be irradiated ● Readout system to be employed (see talk by G. Usai) ● Overview of probes/laboratories for irradiation studies ● CERN X-ray facility ● Planning

6/12 4 different chips (2 samples per chip = 8 samples) ● Some sample already available ● PCBs under construction at CERN to accomodate chips Epi layer thickness samples Max. dose TPAC 1 2 x 12 um standard No deep p-well 2 M TPAC 2 2 x 12 um standard Deep p-well 2 M TPAC 3 2 x 12 um HR Deep p-well 2 M TPAC 4 2 x 18 um HR Deep p-well 2 M

7/12 The CERN X-ray facility for irradiation studies of silicon devices Main parameters of the SEIFERT RP 149 X-ray machine X-ray generator: 2 tubes available (10 & 19 ke. V) Beam diameter up to 1 cm Dose rate: 10 -800 rad/s Calibration through PIN diode Al filters to cut low energy part Large irradiation cabinet Semi-automatic probe station Possibility to accomodate 6”-8” wafers

The probe station inside the irradiation cabinet 8/12

9/12 Recent calibrations of the X-ray facility/1: beam spot location Laser spot X-ray beam spot Relative positions

Recent calibrations of the X-ray facility/2: dose rate vs current 10/12

11/12 Dose [rad] Monitor IDD Threshold scan w/ test-pulse Signal across matrix (55 Fe) Uniformity scan w/testpulse Pre irradiation x x 100 k x x 200 k x x 500 k x x 800 k x x 1 M x x 1. 2 M x x 1. 5 M x x 2 M x x Post irradiation x x Pending verification of the readout system speed/features. Foresee a LDR irradiation in the next round up to the lowest dose where we see a degradation.

Next steps 12/12 ● Contact and check in more detail availability and conditions of use of the other facilities for irradiation measurements ● Understand irradiation conditions within the ITS upgrade program ● Evaluate and test equipment needed (electronics, …) to characterize sensors before/during/after irradiations ● Establish time scale required according to availability of sensors ● Evaluate available manpower and task distribution (expression of interest from Catania, Roma, LNL and LNF)