BARREL 2010 Test Campaign
A. flight 6 quicklook info
The second flight this year (payload A) was launched at about 21:00:53UT
on 17 Dec 2010. This unit used different solar panels, a modified
magnetometer (and a different magnetometer orientation), and no
x-ray detector. Payload A battery temperature starting climbing beyond
normal sunlight-induced variation around
05:00UT on 19Dec. A power disruption occurred near 08:07, resulting in loss
of contact with the payload. CSBF cut down the payload through
an independent cutdown system at 08:58UT. Following cutdown and landing,
there have been multiple short contacts with the payload, in which it
is apparent that the system has been power-cycling.
quick-look pdf plots from flight 6 of the test campaign
B. flight 5 quicklook info
The first flight this year (payload B) was launched at 21:44:36UT
on 13 Dec 2010. The trip to ceiling was unusually slow, but the balloon
is holding altitude nicely. It appears that there was a high voltage
anomaly near 07:09UT on 14Dec 2010, after which the system seems quieter
and has slightly lower gain. Magnetometer offsets are larger than expected.
Power system continues to work nominally.
Flight over: cut down at 00:02UT on 19 Dec 2010, prior to overflying
Australian airspace.
quick-look pdf plots from flight 5 of the test campaign
detector effects of HV anomaly
A detector anomaly can be seen at high time resolution in the four
fast spectrum channels (ch1, ch2,
ch3, ch4).
The lowest energy range shows two count rate spikes
followed by a slow count rate decline. The decline is consistent with the
HV supply oscillator shutting off and discharging---this takes several
seconds, during which time the pmt gain drops. Lower pmt gain means we detect
only the higher energy parts of the spectrum, where the flux is lower.
Hence, the count rates drop, until we see nothing. When the output high
voltage drops low enough, the oscillator restarts and pmt gain quickly
recovers, so counts re-appear.
Uncalibrated slow spectra acquired from the files
that started at 05:40:20 (red trace, before anomaly) and 08:36:11
(blue trace, after anomaly), show changes: the 511keV peak
shifted left, corresponding to a lowering of the high voltage supply,
and noise counts at the low energy end have decreased.
The noise count change at the low end is consistent
with the decreased level and fuzz in the low level discriminator
rate counters.