Development of silicon detectors for Beam Loss Monitoring at HL-LHC

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Development of silicon detectors for Beam Loss Monitoring at HL-LHC E.

Petersburg, Russian Federation B. Dehning, M. R. Bartosik, A.

Egorov Research Institute of Material Science and Technology, Zelenograd, Russian

1 Development of silicon detectors for Beam Loss Monitoring at HL-LHC E. Verbitskaya, V. Eremin, A. Zabrodskii, A. Bogdanov, A. Shepelev Ioffe Institute, St. Petersburg, Russian Federation B. Dehning, M. R. Bartosik, A. Alexopoulos CERN, Geneva, Switzerland N. Egorov Research Institute of Material Science and Technology, Zelenograd, Russian Federation J. Härkönen Ruđer Bošković Institute, Zagreb, Croatia A. Galkin Centre of Technical Support "NAUKA", Russian Federation IPRD16 Oct 3-6, 2016, Siena, Italy 1

2 Outline Motivation and Silicon Beam Loss Monitor (BLM) concept Silicon CryoBLM project In situ irradiation tests of Si detectors at 1.9K - Detectors and experimental methods - Experimental results: signal vs. bias voltage and fluence dependences and signal statistics Simulation of irradiated detector signal Summary 2

limited because of the collision debris masking the beam loss signals. N.B. Loss of 3 10-7 of nominal beam over 10 ms can create a quench at 7 TeV!

3 Motivation and Silicon Beam Loss Monitor (BLM) concept BLM signals exceeding the protection thresholds trigger the beam abort system. Problem: Existing BLMs (gaseous detectors) are located outside the cryostat of superconducting triplet magnets Accurate measurement of the energy deposition into the magnet coils is limited because of the collision debris masking the beam loss signals. N.B. Loss of of nominal beam over 10 ms can create a quench at 7 TeV! Solution: Place BLM sensor close to the magnet coil or integrate it into the coil construction increase of BLM sensitivity New task: Upgrade of Beam Loss Monitoring system of HL-LHC based on solid-state detectors Initiated by CERN BE-BI (Beam Div., Beam Instrumentation) 3

CryoBLMs Requirements to BLM sensors: Compactness and appropriate radiation hardness Possible candidates: Solid-state detectors placed inside superfluid helium (1.

4 CryoBLMs Requirements to BLM sensors: Compactness and appropriate radiation hardness Possible candidates: Solid-state detectors placed inside superfluid helium (1.9K) as close as possible to the superconducting coils (CryoBLMs) measured dose of relativistic protons more precisely corresponds to the dose deposited into the coil. silicon and diamond detectors Arguments to develop CryoBLMs on silicon detectors 1. Industrial base for mass-production 2. Reproducibility of characteristics 3. Compactness 4. Cost effectiveness Question/challenge: radiation hardness of Si detectors at T~(2-4)K? 4

5 Radiation damage in Si at cryogenic T Available: renewed wide knowledge on radiation damage of Si p-n junction detectors at RT and slight cooling (down to -50 C) CERN RD collaborations, experiments at LHC operate at n eq /cm 2 Earlier: raw silicon at T = 4-100K: Interstitials mobile at T~4K Vacancies (V+, V-) - mobile at: T~70K (standard n-si) T~150K (standard p-si) T~ 200K (high resistivity Si) G. D. Watkins, EPR of Defects in Semiconductors: Past, Present, Future, Phys. of Solid State, 41 (1999) G. D. Watkins, Defects and diffusion in silicon processing, Ed. T. D. De la Rubia, et al.; MRS Sypm. Proc. Vol. 469, Pittsburgh (1997) 139. Expected radiation damage at LHe T: formation of vacancy-related defects critical for degradation is suggested to be suppressed 5

6 Silicon CryoBLM project Partnership: CERN BE-BI-BL + Ioffe Institute + CERN-RD39 (since 2011) Experimental Planning of experiments Advancing of BLM construction and technology Experiments preparation In situ radiation tests BLM prototypes - fabrication and installation on the LHC magnets Physics - new knowledge on: o Si detectors operation in Superfluid Helium (T = 1.9K) o Radiation damage in p-n junction detectors at LHe T o Physics of carrier transport and trapping in irradiated silicon P-I-N structures at LHe T Requirements T = 1.9 K Integrated dose ~1x10 16 p/cm 2 (~2 MGy in 20 year); Linear detector response between 0.1 and 10 mgy/s (the range of signals expected close to the quench), and faster than 1 ms; Magnetic field of 2 T and a pressure of 1.1 bar; 6 Stability within operation time of several years.

Milestones of CryoBLM R&D 2012 first test of Si PIN detector operation at 1.9 K: proof of concept In situ radiation tests (the only method of experimental study at 1.

7 Milestones of CryoBLM R&D 2012 first test of Si PIN detector operation at 1.9 K: proof of concept In situ radiation tests (the only method of experimental study at 1.9K) 2012 in situ radiation Test 1 at 1.9K: regular detectors (300 mm) 2014 in situ radiation Test 2 at 1.9K: thin BLM (100 mm), first Si BLM modules installation at LHC 2015 in situ radiation Test 3 at 1.9K: statistics of data Superfluid helium barrel detector T = 1.9K required BLM amount = number of magnets 2 7

In situ radiation tests: experimental Cryogenic system

3 10 11 p/cm 2 per 400 ms spill (~10 10 p/s on

8 In situ radiation tests: experimental Cryogenic system for cooling to 1.9K Irradiation at CERN PS 23 GeV protons, beam diameter ~1 cm at the detector location Beam intensity p/cm 2 per 400 ms spill (~10 10 p/s on detectors) Fluence to p/cm 2 Beam position monitoring (BPM + Si beam telescopes) Test 3 Test 1 8

5 Wcm; thickness d: 300 mm and 100 mm Detector operation at reverse and forward bias mode; forward Current Injected Detectors (CID) Measurements Spill shapes Electrical

9 In situ radiation tests: detectors and measurements P+/n/n+ silicon pad detectors designed and processed by consortium of the Ioffe Institute, St. Petersburg, and Research Institute of Material Science and Technology, Zelenograd, both Russia n-si, r: kwcm, 500 Wcm and 4.5 Wcm; thickness d: 300 mm and 100 mm Detector operation at reverse and forward bias mode; forward Current Injected Detectors (CID) Measurements Spill shapes Electrical characterization (I-V) Signal - collected charge Q c determined by integrating the detector output DC current over the 400 ms spill Pulse response, TCT, LeCroy WavePro, 3 GHz bandwidth, 630 nm laser, width 45 ps (Test 1) Duration of tests: 4-6 weeks 9

10 Charge/MIP (fc) Charge/MIP (fc) Charge/MIP (fc) Charge/MIP (fc) 0.1 Results of in situ irradiation Tests 1 and 2: collected charge vs. F and V 10 1 Si 10 kwcm Test 1; 300 mm V rev (V): Fluence (1x10 14 p/cm 2 ) Q c ~ F -1 Q o ~ d Test 2; 300 and 100 mm 100 mm Voltage (V) 300 mm Fluence (p/cm 2 ) 6.7x x x mm Q o (300)/ Q o (100) = mm 10 0 Si 10kWcm CID (V forw ) 0.1 Fluence (p/cm 2 ) 6.7x x x F (p/cm 2 ): 8x x x x Voltage (V) Voltage (V) Unexpected result degradation rate higher than at RT 10

11 In situ irradiation Test 3 Goals of BLM development for in situ Test 3 (2015) Proof of concept Structure optimization + Statistics Regular detectors (d = 300 mm) Thin bulk detectors (d = 100 mm) Thin bulk detectors (100 mm) with I-V stabilization structure Receiving statistical data upgrade of modules, cryostat and DAQ system 11

12 Set of modules with Si detectors module detector material thickness area, operational purpose amount (um) metallization voltage Tele-IN 4 Si, >15kW cm x12 mm2, solid 200 V Telescope "IN" MM-1 4 Si, >15kW cm 300 5x5 mm2, solid 400 V statistics MM-2 4 Si, 0.5 kw cm 300 5x5 mm2, solid 500 V statistics MM-3 4 Si, >15kW cm 100 5x5 mm2, solid 500 V statistics MM-4 4 Si, >15kW cm 100 5x5 mm2, solid 400 V statistics TCT-1 1 Si, >15kW cm 300 5x5 mm2, grid 400 V CERN-DAQ TCT-2 1 Si, >15kW cm 300 5x5 mm2, grid 400 V CERN-DAQ Spare 0 Spare 0 TeleOUT 4 Si, >15kW cm x12 mm2, solid 200 V Telescope "OUT" Ioffe DAQ Tele-In and Tele-Out silicon beam telescopes Total amount 8 modules, 26 detectors 12

13 Cassette with detectors modules Silicon Beam Telescope module TCT modules Multi-module construction beam 13

14 Electronics and data acquisition & processing 1. Multichannel CERN-DAQ system 2. Multichannel DAQ system of Ioffe Institute for statistical study (new) Permanent on-line registration during 3 weeks of experiment 16 inputs Ampl 16 channel sampling unit & ADC Flash memory Digital Trigger & DAQ PC 14

13 10 15 p/cm 2 Irradiation at CERN PS 23 GeV

(6-7) 10 10 p/cm 2 Maximal current induced by

15 Detector signals from spills p/cm p/cm 2 Irradiation at CERN PS 23 GeV protons Spill: Duration ms Intensity ~ (6-7) p/cm 2 Maximal current induced by spill - ma Data from CERN-DAQ system Detectors: TCT1 (Ch1), TCT2 (Ch3) d = 300 mm p/cm 2 15

16 Signal (arb. units) Signal (arb. units) Signal (arb. units) Signal (arb. units) Test 3: statistics of signals, Q c vs. F Data from Ioffe DAQ system; 16 detectors from modules MM1-MM MM-1 detector # MM mm 100 mm Fluence (p/cm 2 ) Si 15 kwxcm 300 mm Si 500 Wxcm 300 mm MM-3 detector # MM-4 Fluence (p/cm 2 ) Si 15 kwxcm 100 mm Si 15 kwxcm 100 mm 100 mm: - deviations within 10% - maximal signal is not at F = detector # detector # Fluence (p/cm 2 ) Fluence (p/cm 2 ) 16

10-1 10-2 10-3 -400-300 -200-100 0 100 200 300

8x10 13 100 mm, 1x10 15 In irradiated detectors

17 Charge/mip (fc) Test 3: Q c vs. V (voltage scans) 10 1 Different thickness Voltage (V) 300 mm, 3.8x mm, 1x mm, 3.8x mm, 3.8x mm, 1x10 15 In irradiated detectors signal is larger in 100 mm samples At medium F signal is larger in the CID mode At higher F signal is insensitive to bias polarity 17

18 Physics: Approximation of Q c (F) curves using Hecht equation (trapping) Q c v et e e w 1 vet e w 1 exp v et e v ht h w w 1 vht h w 1 exp vht h w V rev T 1.9 K RT b e (cm 2 ns -1 ) x10-16 b h (cm 2 ns -1 ) x10-16 Drift velocities at 4K at F = 0: v es = 1.2x10 7 cm/s v hs = 7x10 6 cm/s Procedure and main parameters EXCEL worksheet, numerical calculation/simulation Poisson equation combined with the rate equation one-dimensional approach for detector geometry, E = E(x) Variable: F, T, V Radiation defects: DAs E c 0.53 ev; DDs E v ev 1/t e,h = b e,h F eq ; b trapping probability constant b is larger at 1.9K 18

19 Summary Scientific results The rate of signal degradation rate at 1.9K is higher than at RT. Defined are: - carrier saturation velocities and mobilities in nonirradiated Si detectors at 4K, - trapping time constants vs. F dependences at 1.9K. Assumed: radiation defect formation at 1.9K - vacancy-related defects are induced? Practical results Si detectors can operate at 1.9K after irradiation up to F = p/cm 2 required for application as BLMs. Operation in CID mode is advantageous up to F ~ p/cm 2.. Thin (100 mm) detectors give higher signal, lower rate of signal degradation and minimal deviations of the signal. Publications C. Kurfürst, et al., Nucl. Instrum. Meth. A 782 (2015) 149. E. Verbitskaya, et al., Nucl. Instrum. Meth. A 796 (2015) 118. Z. Li, et al., Nucl. Instrum. Meth. A 824 (2016) 476 and references herein. 19

20 Acknowledgments This work was performed: - within the framework of Agreement on Scientific Collaboration between CERN-BE-BI-BL group and Ioffe Institute, - in the scope of the CERN-RD39 collaboration program, and supported by the Fundamental Program of Russian Academy of Sciences on High Energy Physics and Neutrino Astrophysics. Thank you for attention! 20

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