1. Summer Student Presentation
Radiation Monitoring
with commercial
p-i-n diodes
BPW34F
Summer Student Project of Kim Temming
Supervisors: Michael Moll
Maurice Glaser
Friday, 3rd of September
By Kim Temming

2. Summer Student Presentation Kim Temming
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
first conclusions
outlook
Summer Student Presentation Kim Temming

3. Summer Student Presentation Kim Temming
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)
Summer Student Presentation Kim Temming

4. Summer Student Presentation Kim Temming
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
Summer Student Presentation Kim Temming

5. How to measure radiation?
increase of voltage with fluence for constant current when biased in forward direction
Summer Student Presentation Kim Temming

6. Summer Student Presentation Kim Temming
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)
Summer Student Presentation Kim Temming

7. Summer Student Presentation Kim Temming
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
Summer Student Presentation Kim Temming

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
Summer Student Presentation Kim Temming

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
Summer Student Presentation Kim Temming

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
Summer Student Presentation Kim Temming

11. Problems of first setup
diodes are very sensitive to temperature
measured voltage depends very much on the temperature
of diode
temperature is measured 2 cm away from diode /
isolated by plastic and air
possible sources of temperature differences
changes of room temperature (air condition!)
touching of diodes
opening of box
another possible explanation:
diodes show peltier effect
cooling down by applying current
necessary to control temperature
of diode very exactly
Summer Student Presentation Kim Temming

12. Summer Student Presentation Kim Temming
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
Summer Student Presentation Kim Temming

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
Summer Student Presentation Kim Temming

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
Summer Student Presentation Kim Temming

15. Problems of temperature / Keithleys
not completely clear yet:
effect of temperature in diode?
effect of room temperature in Keithleys?
limit of keithley accuracy!
Summer Student Presentation Kim Temming

16. Summer Student Presentation Kim Temming
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)
Summer Student Presentation Kim Temming

17. Summer Student Presentation Kim Temming
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, , 100 degree celsius
End
Summer Student Presentation Kim Temming