Initial Results from SLAC ESTB T-506 Irradiation study
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Initial Results from SLAC ESTB T-506 Irradiation study FCAL Workshop, DESY-Zeuthen 7-8 October 2013 Bruce Schumm UC Santa Cruz Institute for Particle Physics. T-506 Motivation. BeamCal maximum dose ~100 MRad/yr Beam Calorimeter is a sizable: ~2 m 2 of sensors.

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Initial Results from SLAC ESTB T-506 Irradiation study

FCAL Workshop, DESY-Zeuthen

7-8 October 2013

Bruce Schumm

UC Santa Cruz Institute for Particle Physics


T 506 motivation
T-506 Motivation

  • BeamCal maximum dose ~100 MRad/yr

  • Beam Calorimeter is a sizable: ~2 m2 of sensors.

  • A number of ongoing studies with novel sensoers: GaAs, CVD diamond

  • Might mainstream Si sensors be of use?

  • Some reasons for optimism…

  • Sensors are in unusual regime: ~ 1 GRad of e+/e-; 1014 n/cm2 after several years.

  • There are on-going studies with GaAs, Diamond, Sapphire materials (FCAL report, Nov 2009).

  • We’ll concentrate on mainstream Si technology polished by decades of technical development.

  • There is some evidence that p-type Si may be particularly resilient:

  • Neutron flux does not seem to be a problem for Si (RD50 findings).

  • There are very few e+/e- radiation hardness studies:

    • S. Dittongo et al (2005); n/p-type Si;160 MRad of 900 MeV e-

    • J.M. Rafi et al (2009); n-type Si; 1.7 GRad of 2 MeV e-

  • Our region of interest is ~100 MeV (incident) and lower (shower max)


Departure from NIEL (non-ionizing energy-loss) scaling observed for electron irradiation

NIELe- Energy

2x10-2 0.5 MeV

5x10-2 2 MeV

1x10-1 10 MeV

2x10-1 200 MeV

G.P. Summers et al., IEEE Trans Nucl Sci 40, 1372 (1993)

Also: for ~50 MRad illumination of 900 MeV electrons, little loss of charge collection seen for wide variety of sensors

(S. Dittongo et al., NIM A 530, 110 (2004)

But what about the hadronic component of EM shower?

3


G.P. Summers et al., IEEE Trans Nucl Sci observed for electron irradiation40, 1372 (1993)

4


More notes
More notes: observed for electron irradiation

  • Neutron flux does not seem to be a problem for Si (RD50 findings).

  • There are very few e+/e- radiation hardness studies:

    • S. Dittongo et al (2005); n/p-type Si;160 MRad of 900 MeV e-

    • J.M. Rafi et al (2009); n-type Si; 1.7 GRad of 2 MeV e-

  • Our region of interest is 100 MeV – 10 GeV (incidence) and lower (shower max)

5


BeamCal Incident Energy Distribution observed for electron irradiation

e+/e- ENERGY (GEV)

BUT: Most fluence is at shower max, dominated by ~10 MeV e-, e+ and . Why might (?) incident energy matter?

6


NIEL (Non-Ionizing Energy Loss) observed for electron irradiation

  • Conventional wisdom: Damage proportional Non Ionizing Energy Loss (NIEL) of traversing particle

  • NIEL can be calculated (e.g. G.P. Summers et al., IEEE Trans Nucl Sci 40, 1372 (1993)

  • At EcTungsten ~ 10 MeV, NIEL is 80 times worse for protons than electrons and

  • NIEL scaling may break down (even less damage from electrons/psistrons)

  • NIEL rises quickly with decreasing (proton) energy, and fragments would likely be low energy

  •  Might small hadronic fractions dominate damage?

7


Hadronic Processes in EM Showers observed for electron irradiation

  • From what we have seen, there are three main processes for generating hadrons in EM showers:

  • Nuclear (“giant dipole”) resonances

  • Photoproduction

  • Nuclear Compton scattering

  • Rates, CBAF, Vitaliy’s picture…

8


9 observed for electron irradiation


10 observed for electron irradiation


11 observed for electron irradiation


12 observed for electron irradiation


13 observed for electron irradiation


Sensor + observed for electron irradiation

FE ASIC

DAQ FPGA

with Ethernet

14


15 observed for electron irradiation


16 observed for electron irradiation


Irradiation plan
Irradiation Plan observed for electron irradiation

  • Intend on using left-over sensors from ATLAS sensor R&D (made at Micron). Both n- and p- type, Magnetic Czochralski and Oxigenated Float Zone.

  • Plan to use NL-CTA beam at 120 MeV (with degrader).

  • Will assess the bulk damage effects. This will further assess the breakdown on NIEL scaling (x50 at 2 MeV and x4 at 900 MeV) in the energy range of interest.

  • An interesting possibility is to mimic the expected radiation tail with an absorber, to be less dependent on radiation damage modeling.

  • Want to also characterize the charge collection efficiency.

Sensors

Sensor +

FE ASIC

DAQ FPGA

with Ethernet


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