Summer Student Presentation

1
Summer Student Presentation

• Radiation Monitoring
• with commercial
• p-i-n diodes
• BPW34F
• Summer Student Project of Kim Temming
• Supervisors Michael Moll
• Maurice Glaser

2
Outline

• purpose of my project
• diode BPW34F / BPW 34
• how to measure radiation with this diodes?
• history of my measurements
• irradiations
• first setup
• measurements / results
• problems
• new setup
• measurements
• first results
• problems
• first conclusions
• outlook

3
Purpose of my Project

• investigate the possibility to use commercial
  BPW 34 p-i-n
• diodes as dosimeters for LHC experiments and
  irradiation
• facilities
• advantages
• commercial product low costs (1.60 )
• robust and easy to handle
• large fluence range (1012 1015 p/cm2)
• measuring NIEL (displacement damage)
• disadvantages
• needs qualifying
• temperature fluence dependence
• annealing
• readout scheme
• commercial product (no influence on production)

4
Diode BPW34F / BPW34

• commercial SI-pin-diode / cheap
• BPW34 photosensitive from 400nm to 1100nm
• (BPW34F 950nm)
• applications
• IR remote controls
• photointerruptors
• control and drive circuits

BPW34
-
photosensitive area

BPW34F
5
How to measure radiation?

• increase of voltage with fluence for constant
  current when biased in forward direction

6
My Work Irradiations

• 102 diodes were irradiated with 24 GeV/c PS
  proton beam
• 50 BPW34F from USA
• 1.0 E15, 0.5 E14, 0.3 E14, 1.0 E14, 0.5 E13, 0.3
  E13,
• 1.0 E13, 0.5 E12, 0.3 E12, 1.0 E12 (all in
  p/cm2)
• 22 BPW34F from MALAYSIA
• 1.0 E15 ppcm2, 1.0 E14 p/cm2
• BPW34 Siemens, BPW34 Osram and BPW34FS
• each 5 pieces 1.0 E13 p/cm2
• each 5 pieces 1.0 E14 p/cm2
• irradiations successful in
• limits of 20 discrepancies
• to wanted fluence
• (ca. 8 errors on values)

7
First Setup

• aluminium box / completely dark
• (diodes are sensitive to daylight!)
• Keithley 2400
• set current / read voltage
• sensor for temperature
• inside box / 2 cm beside diode
• sensitivity 0.1 degree celsius
• labview program
• option for constant current
• option for pulsed current
• displays graph

voltage
time
8
Measurements / results first setup

• VI measurements of all samples before
  irradiation
• current between 0.1 ?A and 1 mA
• results of VI measurements before irradiation
• nearly all samples show same characteristic
• all differences between samples become larger
  with
• higher current
• samples from Siemens
• old (some years)
• vary more than 20

samples siemens
9
Measurements / results first setup

• dependence of the voltage on readout frequency
  and
• readout pulse length
• 10 samples together irradiated with 1.0 E14
  protons/cm2
• applied current 1 mA
• pulse length varying between 1 ms and 1 s
• pulse to pulse time between 60 s and 3 s
• Results of dependence on readout frequency
  pulse length
• not very sensitive
• to pulse length
• (except of constant current)
• not at all sensitive to
• time between pulses
• but differences of more
• than 20 between the
• different diodes

10
Measurements / results first setup

• dependence on readout current
• ONE diode irradiated with 1.0 E14 protons/cm2
• pulse to pulse 3 s, pulse length varying
• current varying between 1 ?A and 100 mA
• Results of dependence on readout current

11
Problems of first setup
12
New setup

• peltier element below socket of diode regulates
• temperature of diode to exactly 19.3 ? 0.01
  degree celsius
• temperature read out by small temperature sensor
  
• (operated with Keithley 2410)
• readout of diode still with Keithley 2400
• temperature displayed on web with webDAQ/100

13
Measurements with new setup

• ONE diode irradiated with 1.0 E14 protons/cm2
• always same end value with constant current
• first no room temperature effects (outside box)
  visible
• because of the good temperature shielding
• over night / weekend measurements
• irradiated diode
• non irradiated diode
• very temperature stable resistor
• measurements
• applied current 100?A, constant current
• temperature measured inside and outside the box
  with 2
• digits
• voltage measured with labview-program and
  Keithley
• 2400

14
First results (new setup)

• irradiated diode voltage still depending on
  temperature
• but very sensitive
• not irradiated diode
• same results but
• less amplitude
• 1 k Ohm resistor

15
Problems of temperature / Keithleys

• not completely clear yet
• effect of temperature in diode?
• effect of room temperature in Keithleys?
• limit of keithley accuracy!

16
First conclusions

• before irradiations
• all diodes very close together, only few
  discrepancies on readout voltage
• after irradiation
• diodes show discrepancies of up to 20 on
  readout voltage
• diodes very temperature sensitive
• temperature needs to be controlled
• best readout scheme
• current 100 ?A
• pulse length 1 ms
• pulse to pulse 3s (not very sensitive)

17
Outlook

• continue measurement
• more different devices (to get statistics)
• more sensitive temperature control
• dependence on the readout temperature
• for fluences 1.0 E12...E15 p/cm2
• from 10 C to 30 C
• dependence on the fluence
• 1.0 E12 p/cm2 up to 1.0 E15 p/cm2
• annealing of samples in oven
• 40, 60. 80, 100 degree celsius