SiPM Radiation Hardness Test

SiPM Radiation Hardness Test in Hall A

3x3 mm2 SiPM Test in Hall A

Test Condition

• Time: 04/20/2010 12:30 PM
• Location: Hall A beam left
• Initial Dose
  • Neutron (rad44_p2) 18.4 mRem
  • Gamma (rad44_p1) 61900 mRem
• Radiation Chips
  • Neutron Rod: serial# 2A01 close to SiPM
  • TLD: serial# 9597, close to SiPM and rad44_p2
  • TLD: serial# 9598, close to rad44_p1 at entrance

Plots

• Change of draw Current and signal shape at working condition as a function of radiation

Neutron and gamma radiation and temperature during the test

Bias voltage was adjusted based on temperature and the draw current increases rapidly with radiation.

Signal Amplitude gradually decreases as a function of radiation dose while no change of its width observed.

• Comparison of VI response before and after radiation

VI curve of Hamamatsu SiPM unit before radiation

VI curve of Hamamatsu SiPM unit after radiation

VI curve of SensL SiPM unit before radiation

VI curve of SensL SiPM unit after radiation

Comparison of VI curves of Hamamatsu unit before and after radiation

Comparison of VI curves of SensL unit before and after radiation

• Signals recorded by oscilloscope show the effect of radiation on amplification: red (initial) -> violet (final)

Signals of Hamamatsu SiPM with radiation growing

Signals SensL SiPM with radiation growing

• If we take the dose to fluence coefficient of 1 MeV Neutron: 400 pSv.cm2 = 4x10-8 rem.cm2 (1 mrem/H -> 6.9 n_eq/s/cm²), we have the following plot

The draw current increment as a function of 1 MeV equivalent neutron fluence

Aneeling of Radiation Damage

Recovery of SiPM dark current, fit with initial point.

Recovery of SiPM dark current, fit without initial point.

Recovery of SiPM gains, fit without initial point.

Facts and Conclusions

• Hall A radiation level is extremely high during P-REX experiment: 50uA on 0.5mm Pb target (9% radiation length).
• A lot of energy dumped to the 2 pieces of collimator behind Pb Target: estimated 1 kiloWatt total power dissipated on them.
• The neutron dose rate before the collimator installed was 1.55 rem/H with 45 uA beam on Pb target. After the collimator was installed, the dose rate during the SiPM test was 1.35 rem/H with 50 uA beam. Therefore the tungsten collimator did not significantly change the radiation level.
• Radiation causes draw current to increase no matter whether bias voltage is applied.
  • Hamamatsu: starting from 8 uA, 5 uA/Rem
  • SensL: starting from 155 uA, 40 uA/Rem
• The dark current from both SiPM samples recovered by about 50% with time constant of 10 days
• Taking the bias voltage adjustment into account, the dark current has an exponential relation to the ambient temperature:
  • I(dark) ~ exp(a*(T-T0))
  • a for Hamamatsu: 0.061±0.003/C
  • a for SensL: 0.047±0.002/C
• Radiation slowly affects the amplification of SiPM but has no effect on the signal width, even though, the drops of the gain get fully recovered afterward.
• Report to GlueX meeting (2010/05/10): link to docDB
• Dark rate measurement shows a increase of noise level consistent with the increase of dark current:Carl's report
  • I(dark) ~ Sigma(pedestal)^2

1x1 mm2 SiPM Test in Hall A

Test Condition

• Same location as previous 3x3 SiPM test: 135 degrees, 20 meters
• Not powered
• Temperature: ~ 21.3 degree C
• SiPM information:
  • Type Number: S10362-11-050C
  • Serial Number: 1260
  • Vop: 71.54 V
  • M: 7.50e+5
  • Dark Rate (0.5 p.e.): 536 kcps
  • Dark Rate (1.5 p.e.): 44 kcps
  • X-talk: 8.2%
  • PDE (lambda = 490 nm): 36.5%
  • At 25 degree C

Initial Neutron Dose 2010/06/11 11:20 AM

• rad44_p2_dose: 0 Rem

Final Neutron Dose 2010/06/15 10:00 AM

• Total dose: 34.3 Rem (NOT corrected by neutron probe efficiency)
• 

Test Result

• ADC dark spectrum before irradiation

• ADC dark spectrum post irradiation

• ADC dark spectrum 2 months later

• Note
  • The pre-amplifier used in the first two tests (before and post) was from Stepan with a total gain of 105 while during the last test (anneal) the pre-amplifier from Fernando was used with a gain of 65.
  • Permanent damage increases dark rate by 21
  • Permanent damage increases dark current by 18: Carl's measurement
  • Cross-talk: 15%

Test with RadCon AmBe Source

Test Condition

• The AmBe source has an narrow neutron energy spectrum averaged at 4 MeV [1] page82
• The AmBe source in RadCon has the following dose rate:

 dose rate = [13/D2]*[1+(0.248*D)2.2375*e-0.3536*D] mrem/H

where D is the distance from the source in the unit of meter

• One 1×1 mm² and one 3×3 mm² SiPMs together with their pre-amplifiers were irradiated by this source
• The distance is 17 cm and dose rate is 0.45 rem/H
• Test started at 14:40 July 12, 2010
• Test stopped at 14:25 July 15, 2010
• Total dose: 32±2 rem

Results

• Increase of dark current:
  • 1×1 mm²: 6.4
  • 3×3 mm²: 7.1
  • average: 6.8
  • expected increase of dark current after annealing (time constant: 10 days, radiation: 72 hours, measurement: 96 hours): 4.2

ADC Dark Spectrum

1x1 mm SiPM

• Before irradiation

• After irradiation

• 1 month later

• Note
  • Permanent damage increases dark rate by 3.5
  • Permanent damage increases current rate by 4: Carl's Measurement
  • Cross talk: 13%

3x3 mm SiPM

• Before irradiation

• After irradiation

• 1 month later

• Note
  • Permanent damage increases dark rate by 4.1
  • Permanent damage increases current rate by 4.7: Carl's Measurement
  • Cross talk: 14%

Damage Conversion and Fluence Simulation of Hall A

Interpret neutron flux into rem and fluence

• Equivalent neutron radiation damage to silicon detector normalized to 1 MeV neutron [2], as recommended for LHC silicon detector study.

• Neutron dose equivalent conversion coefficients were taken from ICRP 74, plot see [3], may off by a factor of 2.

Updated Hall A simulation

• Neutron Energy spectrum [4]

• Dose rate to fluence: 1 mrem/H → 6.7 n_eq/s/cm²
• Dose rate: 3.1 rem/H (1.3 rem/H measured)
  • Ideal dose rate with 0.5 mm Pb target and 50 μA is 7.6 rem/H
  • Actual target thickness was reduced to 40% due to the beam damage
    • 03/28/2010 11:00: 950 mrem/H@22.8 μA → 2.12 rem/H@50 μA (Pb#3 first time in beam)
    • 04/06/2010 07:00: 1.53 rem/H@44.2 μA → 1.73 rem/H@50 μA (Pb#3 last time w/o collimator)
    • 04/16/2010 02:00: 0.99 rem/H@18.0 μA → 2.75 rem/H@50 μA (Pb#3 first time w/ collimator)
    • 04/20/2010 22:00: 1.41 rem/H@49.7 μA → 1.42 rem/H@50 μA (Start of SiPM test)
    • 04/22/2010 09:00: 1.30 rem/H@49.5 μA → 1.31 rem/H@50 μA (End of SiPM test)
  • 1 MeV equivalent neutron fluence: 21000 n_eq/s/cm²

AmBe neutron source

• Neutron Energy spectrum

• Dose rate to fluence: 1 mrem/H → 9.3 n_eq/s/cm²
• Dose to permanently increase dark current by factor of 10: 76 rem
  • 1 MeV equivalent neutron fluence: 2.5×10⁹ n_eq/cm²

Agreement of Hall A simulation and measurement

• In Hall A, with Pb target, it took 35 rem(NOT corrected by neutron probe efficiency, 27 hours) to permanently increase the Hamamatsu 3×3 SiPM dark current by a factor of 10.
• 35 rem → 8.4×10⁸ n_eq/cm².
• Recorded dose rate is 1.3 rem/H.
• If we assume that the neutron probe underestimate the neutron dose in Hall A because it's not sensitive to high energy neutron (E>20 MeV)
  • The correction factor should be: 2.5×10⁹/8.4×10⁸ = 3.0
  • The actual dose rate is 1.3×3.0 = 3.9 rem/H !
  • Quite consistent with Pavel's calculate (3.1 rem/H) now!

Fluence simulation of Hall D

Pavel recently updated his simulation for the neutron flux through SiPMs with normal Hall D production condition.

Simulation Condition and Results

• Detector location: Z = 462 cm
• Rate of photon beam before collimator: 11 GHz
• Dose rates and energy spectra with Hydrogen target
• Flux in downstream SiPM area with Hydrogen target
• Flux in upstream SiPM area with Hydrogen target
• Dose rates and energy spectra with Helium target
• Flux in SiPM area with Helium target
• Flux in upstream SiPM area with Helium target

Hydrogen Target

Downstream Detector

• The energy spectrum of neutron from Hydrogen target:

• Dose rate to fluence: 1 mrem/H → 7.1 n_eq/s/cm²
• At 65-90 cm
  • Dose rate: 4.3-3.3 mrem/H
  • Total neutron flux: 90-76 Hz/cm² (54-43 forward, 37-33 backward)
  • Neutron flux > 10 MeV: 4.3-2.6 Hz/cm² (3.1-1.7 forward, 1.2-1.0 backward)
  • 1 MeV equivalent neutron fluence: 31-23 n_eq/s/cm²

Upstream Detector

• The energy spectrum of neutron from Hydrogen target:

• Dose rate to fluence: 1 mrem/H → 7.6 n_eq/s/cm²
• At 65-90 cm
  • Dose rate: 1.0-0.4 mrem/H
  • Total neutron flux: 20-16 Hz/cm² (3.5-3.2 forward, 17-13 backward)
  • Neutron flux > 10 MeV: 0.7-0.4 Hz/cm² (0.1-0.0 forward, 0.6-0.4 backward)
  • 1 MeV equivalent neutron fluence: 8-3 n_eq/s/cm²

Helium Target

Downstream

• The energy spectrum of neutron from Helium target:

• Dose rate to fluence: 1 mrem/H → 7.2 n_eq/s/cm²
• At 65-90 cm
  • Dose rate: 6.5-4.9 mrem/H
  • Total neutron flux: 140-108 Hz/cm² (94-67 forward, 46-41 backward)
  • Neutron flux > 10 MeV: 7.0-4.0 Hz/cm² (5.6-3.0 forward, 1.3-1.1 backward)
  • 1 MeV equivalent neutron fluence: 47-35 n_eq/s/cm²

Upstream

• The energy spectrum of neutron from Helium target:

• Dose rate to fluence: 1 mrem/H → 6.6 n_eq/s/cm²
• At 65-90 cm
  • Dose rate: 1.2-0.8 mrem/H
  • Total neutron flux: 35-28 Hz/cm² (4.0-3.8 forward, 31-24 backward)
  • Neutron flux > 10 MeV: 1.5-1.1 Hz/cm² (0.5-0.1 forward, 1.0-1.0 backward)
  • 1 MeV equivalent neutron fluence: 8-6 n_eq/s/cm²

Compared to Hall A Simulation Result

• To reach 10 times (50% recovery included) higher dark current of SiPM in Hall A: 27 hours of 50 μA beam → 84 rem → 2×10⁹n_eq
• At 65-90 cm (inner-outer radius of BCal), to reach same radiation level:
  • Hydrogen target: 2.0-2.8 years for downstream and 8-21 years for upstream of full-time running
  • Helium target: 1.3-1.8 years for downstream and 8-11 years for upstream of full-time running

Future Test Plan with Radcon AmBe Source

Tests with previously irradiated samples

• Revisit noisy 1x1 mm² SiPM sample from Hall A
• Uniformity test of the 4x4 3x3 mm² array from Hall A
• Measure permanent damage of all the irradiated samples

Temperature test with AmBe source

• Purchase 12 1x1 samples from Hamamatsu product page
• Set up a DAQ test platform in F117
• Irradiate all of them with AmBe source to 30 rem (4 days), 6 at 0 degree, 6 at room temperature
• Annealing test of all the samples at three different temperatures: 0, 20 and 60 degrees for 20 days

Parasitic Test

• Re-irradiate old samples to see potential change of the damage rate
• Irradiate SiPM used in tagger hall