Measurement of charge collec1on in irradiated miniature sensors for the upgrade of ATLAS Phase-II Strip tracker

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1 Measurement of charge collec1on in irradiated miniature sensors for the upgrade of ATLAS Phase-II Strip tracker Vladimir Cindro Jožef Stefan Institute, Ljubljana, Slovenia S.H. Abidi, A.A. Affolder, M. ArraBa, V. Cindro, B. Ciungu, K. DeKe, Z. Dolezal, C. Escobar, V. Fadeyev, C. Garcia, I.M. Gregor, K. Hara, L.B.A. Holmes, P. Kodys, G. Kramberger, J. Kroll, C. Lacasta, V. Latonova, D. Madaffari, I. Mandić, M. MikesBkova, M. Mikuž, M. Minano, K. Nakamura, R.S. Orr, D. Rodriguez, E. Rossi, U. Soldevilla, J. Suzuki, R. Teuscher, Y. Unno, S. Wada On behalf of ITk collaborabon Vladimir Cindro, HSTD December 2017, Okinawa, Japan 1

2 Outline MoBvaBon IrradiaBons C/V and I/V measurements CCE measurements with Alibava setup Edge TCT measurements Conclusions Vladimir Cindro, HSTD December 2017, Okinawa, Japan 2

Fluences in ATLAS ITk: Strips: 4 barrel layers and 6 forward disks (165 m 2 ) 40 cm r 100 cm Peak instantaneous luminosity up to L = 7.

5 μm pitch in barrel and ranging from 69 μm to 85 μm in disks The maximum 1 MeV neutron equivalent fluences for the barrel and strip end-cap detectors are predicted to be 2.

3 Fluences in ATLAS ITk: Strips: 4 barrel layers and 6 forward disks (165 m 2 ) 40 cm r 100 cm Peak instantaneous luminosity up to L = cm -2 s -1 (pile-up 200) The predicbons of parbcle fluences and ionising doses for the ITk layout assume an integrated luminosity of 3000 i -1 : Strip sensors with 75.5 μm pitch in barrel and ranging from 69 μm to 85 μm in disks The maximum 1 MeV neutron equivalent fluences for the barrel and strip end-cap detectors are predicted to be cm 2 and cm 2, respecbvely. In addibon a safety factor 1.5 is required! Strips at r > 40 cm è neutrons have the largest contribubon to the NIEL! Vladimir Cindro, HSTD December 2017, Okinawa, Japan 3

Miniature sensors: The miniature sensors with n-strips in p-bulk: miniature sensors produced by Hammamatsu on the same high resisbvity FZ 6 inch wafers as prototypes of full size R0 (the first ring

4 Miniature sensors: The miniature sensors with n-strips in p-bulk: miniature sensors produced by Hammamatsu on the same high resisbvity FZ 6 inch wafers as prototypes of full size R0 (the first ring in ATLAS strip endcap) sensors (previous presentabon) outer dimension of 10 mm 2 x 10 mm 2, 325 μm thick 104 readout strips, 8 mm long three different pitches to match the variabon of pitches on "Stereo Annulus sensors 75.5 μm (default) 70 μm (narrow) 84 μm (wide) AC and DC coupled distributed to different labs for irradiabons, electrical tests and charge collecbon measurements irradiabons with protons and distribubon to labs CV/IV measurements / Prague proton irradiated CCE measurements in Japan and Valencia neutron irradiated CCE and TCT measurements in Ljubljana distribubon of work: p irrad CYRIC (Japan) n irrad Ljubljana C/V I/V Prague Japan CCE p Japan Valencia CCE n, Edge TCT Ljubljana Vladimir Cindro, HSTD December 2017, Okinawa, Japan 4

IrradiaBons with 70 MeV protons at CYRIC (Japan): temperature -15 C scanning with sample movement irradiabons 1 hr dosimetry using Al27(p,3pn) Na24 spallabon reacbon damage factor from

5 IrradiaBons with 70 MeV protons at CYRIC (Japan): temperature -15 C scanning with sample movement irradiabons 1 hr dosimetry using Al27(p,3pn) Na24 spallabon reacbon damage factor from RD50 (1.47) equivalent ﬂuence uncertainty 10% 3 ﬂuences: 5.6, 11 and 22 x 1014neqcm-2 storage in the fridge awer irradiabon Vladimir Cindro, HSTD December 2017, Okinawa, Japan 5

IrradiaBons with neutrons : TRIGA reactor at Jožef Stefan InsBtute, Ljubljana damage factor 0.90 for fast neutrons irradiabon flux 1.

6 IrradiaBons with neutrons : TRIGA reactor at Jožef Stefan InsBtute, Ljubljana damage factor 0.90 for fast neutrons irradiabon flux n eq cm -2 s -1 at full power (250 kw) uncertainty of fluences ± 10 % equivalent fluences: 5 x 10 14, and 2 x n eq cm 2 Approx. 2 hours at RT before 1 st CCE measurement Temperature (C) pt100_ pt100_ NTC Time (min) Temperature during the irradiabon Flux per unit of lethargy (èln E) in different experimental channels K. Ambrožič et. al. Applied Radiaton and Isotopes 130 (2017) Vladimir Cindro, HSTD December 2017, Okinawa, Japan 6

7 Total Leakage Current: Pre- and post proton irradia1on ATLAS12EC T=-20 C 2.2E15 n eq /cm 2 1.1E15 5.6E14 T= +20 C non-irrad. Smooth behaviour up to 600V/1000V No breakdown voltage observed in measured interval Leakage current increases with increasing fluence

8 Leakage current per cm 2 of proton irradiated mini s Comparison A12A, A12M, A07 and A12EC Total number of sensor tested 126: Proton IrradiaBons: Karlsruhe, Birmingham, CYRIC Temperature normalized to -15 C, I (T -15 )=I(T M )*(T -15 /T M ) 2 *exp[-e/2k B *(1/T -15-1/T M )], with E=1.2eV Sensors annealed 80 minutes at 60 C Current normalized to 1cm 2 area; AcBve area - Inner dimension of bias ring => A(EC) = 0.69 cm 2, A(barrel, A12EC) = cm 2 Alfa (+20 C) = 4e-17 A/cm, temperature correcbon coefficient between +20 C and -15 C : 33 Leakage currents of new A12EC (R0) sensors are consistent with A12A, A12M and A07 8

9 CV Characteris1cs for Full Deple1on Voltage (FDV) es1ma1on: Pre- and post proton irradia1on ATLAS12EC R0 Non-irradiated sensors: FDV = V (ρ=3.1 kωcm) Cbulk at full deplebon is 25pF Irradiated sensors: FDV increased up to 600 V at 2.2e15n eq /cm 2 increase lower than expected from g c = 0.01 cm V fluence

CCE measurements (Alibava setup) based on analogue Beetle

cooling systems (cold box, PelBer) triggering with

ini) normalizabon to MIP MPV 23100 e-h pairs in 300 μm of

photomulbplier 90 Sr source holder Vladimir Cindro, HSTD11

10 CCE measurements (Alibava setup) based on analogue Beetle chip 25 ns peaking Bme 40 MHz clock 90 Sr source different cooling systems (cold box, PelBer) triggering with scinbllator same seƒngs of Alibava in all labs (kazu.ini) normalizabon to MIP MPV e-h pairs in 300 μm of depleted unirradiated silicon (77 pairs/ μm) cooling block photomulbplier 90 Sr source holder Vladimir Cindro, HSTD December 2017, Okinawa, Japan Al support in thermal contact with cooling block 10

11 Neutron irradiated sensors before (dashed) and awer (solid) annealing 80 min at 60 C: annealing increases charge no difference for different pitches and voltages below 800 V wider pitch gives higher signal before annealing at the highest fluence and above 800V indicabon of mulbplicabon this effect disappears awer annealing (decrease of space charge) Vladimir Cindro, HSTD December 2017, Okinawa, Japan 11

12 Long term annealing at 60 C : short term - decrease of space charge and trapping improves CCE except at voltages above 1000 V where mulbplicabon disappears long term - mulbplicabon at higher voltages increases charge Vladimir Cindro, HSTD December 2017, Okinawa, Japan 12

13 Fluence dependence neutrons: - dashed line before annealing - solid line awer annealing 80 min at 60 C - annealing improves CCE except at the - highest fluence - Wider pitch more mulbplicabon! Vladimir Cindro, HSTD December 2017, Okinawa, Japan 13

14 Comparison with A12: R0 AC def sensors full lines A12 dashed lines - A12 (measured in 2014) Vladimir Cindro, HSTD December 2017, Okinawa, Japan 14

15 Proton irradiated sensors: not annealed samples - dashed lines annealed samples - full lines 80 min annealing at 60 C increases collected charge Vladimir Cindro, HSTD December 2017, Okinawa, Japan 15

16 Fluence dependence ITk largest fluence protons cause less degradabon of signal than neutrons at same NIEL 700 V signal above 12ke o in strip ITk (without safety 500 V signal above 9 ke o Vladimir Cindro, HSTD December 2017, Okinawa, Japan 16

17 Edge TCT measurements: raise of signal è velocity (E ﬁeld) proﬁle integral of signal è charge proﬁle Vladimir Cindro, HSTD December 2017, Okinawa, Japan 17

18 Comparison R0 ATL12 before irradiabon Velocity profile (below deplebon:) Charge profile (above deplebon) RO sensors were not polished! Both sensors have same acbve thickness 300 μm Results consistent with higher resisbvity (lower FDV) of R0 material compared to A12 Vladimir Cindro, HSTD December 2017, Okinawa, Japan 18

19 Comparison R0 ATL12 awer irradiabon with neutrons: Velocity (E field) profile Charge profile Φ = ncm -2 è Φ = ncm-2 A12 nominal resisbvity 3.1 kω, R0 nominal resisbvity 3.5 kω A12 and R0 are more similar at the highest fluence indicabon of acceptor removal Vladimir Cindro, HSTD December 2017, Okinawa, Japan 19

20 Conclusions: pitch variabon does not influence signal up to 800 V at all fluences at the highest fluence mulbplicabon at high voltages wider pitch è more mulbplicabon short term annealing improves signal at lower voltages protons cause less degradabon of signal than neutrons Vladimir Cindro, HSTD December 2017, Okinawa, Japan 20

21 Signal/Noise MulBplicaBon increases signal faster than noise Values are for Beetle chip, short strips, low temperature!! Vladimir Cindro, HSTD December 2017, Okinawa, Japan 21

Why p-type is better than n-type? or Electric field in heavily irradiated silicon detectors

Why p-type is better than n-type? or Electric field in heavily irradiated silicon detectors G.Kramberger, V. Cindro, I. Mandić, M. Mikuž, M. Milovanović, M. Zavrtanik Jožef Stefan Institute Ljubljana,