PWO crystals P. Orsich, K.-T. Brinkmann, V. Dormenev, M. Moritz, - - PowerPoint PPT Presentation

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PWO crystals P. Orsich, K.-T. Brinkmann, V. Dormenev, M. Moritz, - - PowerPoint PPT Presentation

Jan 13, 2024 325 likes •486 views

Studies of Stimulated Recovery of PWO crystals P. Orsich, K.-T. Brinkmann, V. Dormenev, M. Moritz, R.-W. Novotny, H.-G. Zaunick II. Physics Institute JLU, Giessen PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

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SLIDE 1

Studies of Stimulated Recovery of PWO crystals

  • P. Orsich, K.-T. Brinkmann, V. Dormenev,
  • M. Moritz, R.-W. Novotny, H.-G. Zaunick
  • II. Physics Institute JLU, Giessen

Studies of stimulated recovery of PWO PANDA Collaboration Meeting, November 2019

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SLIDE 2

Introduction Experimental setup Results Summary and outlook

  • Introduction
  • Experimental setup
  • Results
  • Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

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SLIDE 3

Introduction Experimental setup Results Summary and outlook

Transmission after the irradiation of crystals with different radiation doses

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

Induced absorbtion vs light yield The irradiation leads to the population of color centers (induced absorbtion) => Degragation of the transmission =>Reduction of the light yield =>Deterioration of the energy resolution

Stimulated recovery with different LED types

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SLIDE 4

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

Schematic layout of the experimental setup

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SLIDE 5

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

Thermoinsulated box Schematic layout of the experimental setup

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SLIDE 6

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

Thermoinsulated box

Board with PWO and VPTT

Schematic layout of the experimental setup

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SLIDE 7

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

Schematic layout of the experimental setup

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SLIDE 8

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

  • Monitoring system

A response of the VPTT on the monitoring signal

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SLIDE 9

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

  • Laser diode system
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SLIDE 10

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

  • Laser diode system

2 modes of the stimulated recovery:

  • “offline” mode - stimulated recovery

process via the illumination after the irradiation (during beam-off periods)

  • “online” mode – the illumination during

the calorimeter operation

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SLIDE 11

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

Dose rate of 4.6 Gy/h during 6.5 h (integral dose = 30 Gy)

Spontaneous recovery of the PWO crystal after the irradiation at +18 C and -25 C

  • no significant

spontaneous recovery at the low temperature during 40 hours of the measurement.

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SLIDE 12

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

Dose rate of 4.6 Gy/h during 6.5 h (integral dose of 30 Gy)

Recovery curves of the PWO crystal after the irradiation as a function of the integral duration of the illumination with blue and infrared laser diodes at +18 C

  • blue light illumination

more effective and a perfect tool for fast recovery

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SLIDE 13

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

Dose rate of 4.6 Gy/h during 6.5 h (integral dose of 30 Gy)

  • stimulated recovery is

accelerated with the increase of the intensity at +18 C.

  • nearly 95% during 2

days

Recovery of the PWO crystal after the irradiation as a function of integral duration of illumination with infrared laser diodes at +18 C with different intensities

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SLIDE 14

Introduction Experimental setup Results Summary and outlook

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

Dose rate of 4.6 Gy/h during 6.5 h (integral dose of 30 Gy)

Recovery curves of the PWO crystal after the irradiation as a function of the integral duration of the illumination with infrared laser diodes at +18 C and -25 C

  • stimulated recovery

process for infrared laser diode at -25 C was observed

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SLIDE 15

Introduction Experimental setup Results Summary and outlook

Summary

PANDA Collaboration Meeting, November 2019 Studies of stimulated recovery of PWO

  • The stimulated recovery process is an effective application to reduce

radiation damage of the EMC units.

  • The stimulated recovery with blue light can be implemented only in

“offline” mode.

  • Since VPTT has a negligible quantum efficiency in the infrared

region, the stimulated recovery with light in this range opens an

  • pportunity for the “online” recovery mode.
  • The infrared laser diode with peak wavelength above 850 nm can be

a possible candidate for “online” recovery mode at low temperature.

  • Further tests to define wavelength limit and minimal intensity at

fixed dose rate. Outlook