Results from the UC Davis 63 MeV proton beam irradiation test.
June 2000 test
Conditions.
The measurements were taken at the UC Davis by N. Bondar (bondar@fnal.gov) and N. Terentiev
(teren@fnal.gov) with help from M. Tripathi (mani@physics.ucdavis.edu), B. Holbrook
(bholbrook@ucdavis.edu) and M. Von der Mey (mey@physics.ucla.edu).
The conditions of the test:
- A 63.3 MeV proton beam at an incident beam angle of 0 degrees with respect to the normal to the board.
- The beam covered all elements of the board including ASIC chip CMP16F (BiCMOS device) itself, input
protection diods (Bipolar devices), power regulator and passive elements.
- Four anode front end 16 channel boards with CMP16F chips on them were tested (boards 5, 7, 8 and 9).
- The board #39 was placed out of beam, tested in parallel with each chip from the list above and was used
as a reference to make sure that other than beam intensity conditions were one and the same.
- The threshold, gain, discriminator offset, time resolution and slewing time have been measured with use
of a test pulser on the CMU ASIC test stand
(stand)
which was moved from Fermilab to the UC Davis for
the test period of time.
Data and specific operating conditions.
Board # 5
- received 7 successive exposures for a total of
80 krad
:
- 20 krad in 4 exposures at beam current of 1.6 nA for approx. 2 minutes each;
- 60 krad in 3 exposures at beam current of 7.0 nA for approx. 2 minutes each.
Board # 7
- received 10 successive exposures for a total of
74 krad
:
- 14 krad in 7 exposures at beam current of 1.6 nA for approx. 1 minute each;
- 60 krad in 3 exposures at beam current of 7.0 nA for approx. 2 minutes each.
Boards # 8, 9
- received 7 successive exposures at beam current of 1.6 nA
for approximately 1 min each, for a total of
14 krad
.
The static parameters(current and voltages) were measured during each exposure.The measurements of
the thresholds,noise, gain and other parameters were done during 10-20 minutes after each exposure.
For the presentation the results were normalized to their initial values obtained before the first exposure.
Results.
-
No latchups or spikes
have been seen up to maximum TID of 70-80 krad.
-
No change in static parameters
(voltages).
-
All 16 ch in boards 5 and 7
stopped to work after receiving about 65-70 krad of TID though their static
parameters remained unchanged. However, a month later both chips were back to life (about details - to N.Bondar).
-
Threshold, noise, gain and discriminator offset
(averaged over 16 channels for each board) are
here
.
Their values before irradiation are given
here
.
The observed threshold is decreasing with the dose due to increasing in the preamplifier gain and discriminator offset.
The overall effect is rather small, about 10-15% for total ionizing dose of 60 krad. Details for each board such as
channel by channel parameters vs exposure number are here (
board 5
,
board 7
,
board 8
,
board 9
) where
pages of interest are 1-2 and 8-9. The noise in channels 8-16 was systematically higher than in ch. 1-7 (see page 2).
This is probably due to extra long cables connected to the boards and serving for voltage and current measurements.
Note that the behavior of the threshold, gain and offset remains the same in both cases (
ch 1-7
and
ch 8-16
).
-
Time resolutions
at Qin=50, 100 and 150 fC (RMS, averaged over first 7 channels for each board) are
here
.
No dependence vs dose. Observed deviations are likely to be due to pickup noise.
-
The slewing time
in the range of Qin=50 - 170 fC (averaged over first 7 channels for each board) and the
mean time
at Qin=50, 100 and 150 fC are
here
. The change in the slewing time is negligible up to TID of 5 krad. It is increasing with
the dose by almost 40% at dose of 40 - 60 krad and is not harmfull to the performance of the electronics. The change in
the mean time is only 2.5% up to TID of 60 krad.
Back to radiation test page
Last modified: Fri Apr 20 12:25:00 CST 2001
teren@fnal.gov
Results.
Conditions.
Data and specific operating conditions.
Results.