DRAGON Meeting October 18th 2005

Present:CR (Chris Ruiz), AP (Anuj Parikh), JC (Jac Caggiano), LE (Luke
Erikson), CW (Chris Wrede), MT (Mike Trinczek), DH (Dave Hutcheon),
JCl (Jason Clark), CD (Chuck Davis), LB (Lothar Buchmann), JP (Jonty
Pearson), DO (Dave Ottewell), AO (Art Olin), PM (Peter Machule), GR
(Goetz Ruprecht), LF(Lisa Fogarty-recorder).

Started 14:00

1)	Minutes of the Previous Meeting

Not yet available.

2)	E989

CR-We have been running with a max current of 5.6enA. The current 
started at about 2.5enA and we have been running at an average4 of 
3enA on FC4 for roughly 68.5 hours.

There is a peak in TOF spectrum, clearly seen. (This spectrum covers 
roughly half the running time. It can be seen on analysis elog: 
“october run offline” it is the first attached image). The peak 
stands out even better after offline analysis.

AP-Is investigating the cuts that need to be applied to the data.

CR-Iris is doing its job but accidental rate will go as the square 
of beam intensity and the beam is much more intense this time around.

DH-Also need to consider the leaky beam fraction, but this seems 
consistent at the moment.

We need to consider what state to have the iris in for subsequent 
runs, as is, more open or more closed etc.

CR-there were some runs where BGO rate went down but leaky beam 
remained the same.

CW-This was at a time when the lasers were being changed.

DH-It was possible that the beam intensity remained the same but the 
Na26 contamination changed. We could ask Ops to try to tweak the ratio 
here, possibly sacrificing some Al26 current, but it may improve the c
ontamination ratio.

JC-MCP is uncalibrated and also a second TAC has been installed giving 
a choice of using timing with the front or back strips on the DSSSD.
CR- This time the x-distribution of the leaky beam is different, 
instead of a smooth tail there is now a double humped tail…unsure 
why this is.

3)	To Do List

Measure MCP efficiency using the attenuated beam.

Ask for a tweak to get a smaller percentage of Na26 contaminant.

Following problems tuning, we should get together with the operator 
and come up with a checklist of things to do to enable the operators 
to accurately tune through the target.

JC-Prior to MCP outage the DSSSD leakage current was ~50nA, it was 
subsequently at 1uA (AP-it has gone down from that value now). This 
may still suggest some damage to the DSSSD.

Possibly put the source in the box to check, since we have time during 
maintenance tomorrow.

CR,AP will do this tomorrow.

CR-Possibly put the source on the MCP foil ladder permanently.

DH-We could also implement cooling of the detector for this run.

4)	AOB

CR-At York they wish to test the heavy ion resolution of some solar 
cell detectors and would like to know if they could passively test 
them on any DRAGON run. They could be mounted on the MCP ladder.

DH-This is possible, we just need to check the schedule.

Meeting Adjourned 14:35