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Our next tasks
Dear Colleagues,
This is just a preliminary working program for next days (9-14 October), that
could go as follows, if DAFNE. as is doing, will continue to improve its
working contiditions.
Remember that the ideal goal is to have all detectors switched ON at the
operative conditions non only with stored beams but also during normal
injections.
Starting from outward toward inward FINUDA
Tofone.
It is already ON, also during injection. Sometime, when beam is lost, but non
always when beam is lost, few PMs go in trip. In general it seems to substain
rather well the DAFNE conditions even in the previous days when beams were not
well tuned and vacuum worse. Work on it should now be a systematic study of its
response and laser calibration (already in progress).
Straws.
Mixture|: Etane 50% Argon 50%.
They should be turned ON at a voltage considered safe and seen how is their
behaviour also during injections. If all is o.k. they should be slowly rised to
their operative voltage, eventually starting with those at the top and bottom,
and verified that they do not discharge when there are stored beams. And then,
if o.k., also during injections.
Drift Chambers.
Mixture|: Isobutane 36%, He 64%.
With beams stored, starting with the outer ones, select the top and bottom (3o
and 7o), switch them on and rise slowly the HV up to the operative voltage. If
all is o.k., verify the signals and repeat the procedure for all other outer
drifts, in the order 2o, 4o, 6o, 8o, 5o and, final, 1o. If all is o.k., try, in
the same order, to take them ON at the operative voltage also during injection.
Eventually determining the maximum HV they can remain during injection.
Repeat the same procedure for the inner drifts, in the order 2i, 3i, 6i,7i, 4i,
5i, 8i, 1i.
Tofino
With beams stored, switch it on increasing slowly the HV, checking rates and
amplitude signals. eventually reach the operative voltage. Is all is o.k.,
take it on also during injections, eventually starting from low HV.
Since tofino enters in the trigger, it is rather urgent to have it tuned in
DAFNE operative conditions.
In particular to verify if it can work at the lower thresholds needed to see
the mips, as are the Bhabha events.
Microstrip.
In principle the same procedure as for the other detectors: switch on with
stored beams and if all is o.k., take them on also during injection, starting
with the modules far from the radial (horizontal) plane.
When detectors are tuned up to tofino, with eventually only microstrip still
left to be checked or under check, it will be possible, if at that time DAFNE
will be able to provide collisions, to start runs trying to see the Bhabha
events and, hence, be able to provide Luminosity. BEFORE this can happen,
however, any problem with the TRIGGER: electronic, logic, timing, tuning .....
must be fixed. And this task should start soon after tofino wil be tuned.
It is advisable, in the first period, to ask DAFNE to run the machine
in "module 4" (one bunch filled followed by three empty bunches, so with a
maximum of 30 bunches per beam), in order to have events due to bunch crossing
separated by about 11 ns (bunches in DAFNE have 2.7 ns separation), reducing
the influence of detector electronic jitter.
Moreover, if we succeed (as we must, uderwise we will loss efficiency in
extracting from DAFNE the integrated luminosity ) to have detectors ON during
injection, we should start a run and leave it active also during injection,
using the injection VETO signal with a properly selected delay, to
automatically inhibit the dirty periods and use at the best the stored
currents, i.e. the furnished Luminosity.
It is clear, rinally, thay particlularly these first phase will require the
presence of rather expert people of the various detectors, since it is not yet
the time for the routine shifts of data taking.
The RUN
COordinator
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