Minute of the week at GSI
March 9-13 1998
Apart from a "black tuesday", the week was generally productive. Here are the
main points.
1- It was checked that the "Event buffer" could be accessed, on line, by an
independent fortran program. The attempt to access the "JBUF buffe"r was
unsuccessful due to the impossibility to extract it from the reaction
chamber PC control. This PC had other problems and was brought back to
GANIL. The readout of the JBUS buffer should be tested in GANIL before
the PC is brought back to GSI.
2- The driving group of the INDRA slow control agreed on the backbone of
this process and on the exchange of information between the "data
acquisition process" and the "visualization process". These processes
should run on a supplementary ALPHA workstation that wil be brought to
GSI on the 20th of April. This workstation should have PAW installed
since it wil be used for the visualisation. It should also have a local
disk with enough space in order to "archive" the different buffers. For
the moment, the interest of the "Bias-Current" buffer is still under
discussion. Responsibilites : M.L.Begemann and W.Muller are un charge of
the visualisation of the slow control. C.O.Bacri and D.Guinet are in
charge of the "Event" buffer treatement and archiving. GANIL (G.Auger)
sould take charge of the "JBUS" buffer treatement and archiving. If
necessary, the "Bias-HT" buffer would be the responsibility of the LPC.
3- The data buffer has been extended to include a VME scaler (unit 18 in the
VME rack) and a CAMAC coincidence register (Lecroy 4448) which will
record the "On/Off Spill" information as well as the proximity (10
microsec.) of a Veto signal (the "scintilateur trou" for the INDRA
coll.). Related direct spectra have been implemented in the standard
INDRA Visu program (names CEL : Control En Ligne). The Aladin group
should inform O.Lopez of the data to be read in and of the calculated
spectra to be visualized with these data.
4- Progress has been made on the compilation of the "Inspection" program.
The LPC has the responsability to push this forward up to the point where
the "widgets" behave properly. The IPN will then take over to implement
the features related to the new Ring 1. The C++ Control programs shoudl
be tested next time : in these, a "fast" feature to On/OF "all" the
discriminators and "detector bias" would be a strong plus.
5- Progress has been made on different items related to the reaction chamber
The motorization of the Ring Diaphragme is now controled by the reaction
chamber PC.
Concerning the video camera, the target-holder has been clearly observed
(with opened Chamber and normal light) on the control monitor. Thanks to
the 80-200 mm zoom lens, it is possible to see the target in small size
with its surround or only the target in big. The next step is to install
lights (normal and IR) to see the target in total darkness.
The connexion (air-vaccum) for diaphragme motor (command and security),
camera and light have been done.
The video signals both from target camera and pc screen (used for
profilors) have been transmitted to the Data Shack and also to the
Hauptkontrolraum (GSI Beam control room) with success.
6- A list of necessary documentations has been written up. It will be sent
to all with suggestions of names of people concerned by the writting up.
7- The "Pulser modes". A discussion has led to the suggestion that the
pulser triggering should be, in GSI, independent of the beam structure.
The pulser events will thus be present "On spill" and "Off spill". In
order to have sufficient pulser events, the suggested time sequence is
considered :
physics : 255 secs
physics+laser : 45 secs
physics : 255 secs
physics+pulser : 45 secs
(reducing each period by 2 could also be considered)
giving thus 1500 pulser (and laser) events per 1/2 hour (approx. a run in
GANIL) with 500 of those "Off Spill".
Info : the dead time of a pulser (or laser) event is 2ms. The supplementary
dead time introduced is therefore of the order of 1% (6sec for each
600sec period). The dead time can be calculated by the following
formula : T(dt)=300+ 5.6*n, where n is the number of detectors hit
(IC, Si, or CsI, corresponding to 6 words (label & data) for each in
the event buffer) and the result in microsecs.
The electronic for the time squencing has been installed. We are looking
into the possiblity of driving the puler-laser frequence (10Hz) by the
"Selecteur" itself. If this is not possible, this could be done
externally. The first solution would simplify the labelling of these
events.
8- The "double peak" problems of the QDC. More than a day and a half has
been devoted to this problem. It has finally been observed that when only
2 modules are present in the VXI rack (with a power consumption of less
that 20A on the 5V) the system behaves well : One well defined peak and
good current stability +/-0.05A. When a third module is introduced
(whichever one it is) the double peak appears and the current is
significantly unstable (+/- 0.5A). Two QDC modules as well as the VXI-QDC
power supply has been brought back to GANIL.
It should be noticed that with a given power supply the double peak
was separated by 20 channels, whereas with another (taken from the
VXI crate below the QDC one) the distance was 70 channels. It is this
one that has been brought back to GANIL.
Hopefully, this phenomenon will be reproduced and fixed in GANIL.
One side benefit of this problem is that we have learnt how to
operate the acquisition system with several crates removed from the
VXI crates. A documentation on how to do this could be written up by
those that have participated (R.Bougault and O.Lopez) for further
use.
Info : The QDC responsible for the data acquisition problems found in
January (IC ring 10-5) has been brought back to GANIL for repair.
9- In the VME initialisation routine, the CAMAC part (initialisation of the
pulsers) was taking enormous time. This has been greatly accelerated
(factor 10) by Bruno Raine. He would like it to be checked.
10-Important : The preceding week have shown us that a monday night to
Friday morning effective week in GSI was too short to really be
productive. It is therefore requested that, in April and May, departure
time is fixed either on Friday evening or on saturday morning.
Our next visit to GSI is planned for the week of 20-25th of April.
------------------------------------------------------------------