When reading the shift reports it would probably be useful to have some information on the triggers.
For this purpose I enclose a summary of the present setup. Hope it show up readable in your favorite e-mail program. If not go to the brahms-l listserver archive.
enc/
Trigger setup for June 2000, running.
Update July 3, 2000
Several triggers was used, in large to be able to find what good collisions triggers might be. What is found in the data so far is based on..
Trigger Number
Function.
Typical scale down factor
1
BB(L)*BB(R)
N(Big Tubes)>=2 narrow
0,1
4
ZDC Yellow * ZDC Blue
DT overlap 14 nsec
E(ZDC) > 25 GeV
1
5
BB(L)*BB(R) wide time
Overlap N(NbigTubes)>=3
0, 20-40
6
2 Big Tubes in each array carefully timed. Narrow dT
1
7
Pulser
Specific pulser selected by Lecroy coincidence units preceding pulser input.
8
Synchronization trigger
rate 1 Hz.
After the startup period we should decide which of these we should really use.
The ZDC coincidence is a very good Min Bias trigger that in fact does pickup even the electromagnetic disassociation events. On the other hand it it sensitive to all of the vertex, which initially has a RMS of about 50 cm (about 2-2.5 times the Blue Book estimates). The timing for this trigger was changed on July 1. Before that time it was late by about 40-50 nsec compared to the beam-beam triggers.
The trigger 6 is from two very well time big tubes in the Left and Right beam beam array. This also select much closer to the nominal vertex (RMS 30 cm).
The goal is to have all the beam-beam counters aligned so the only two triggers will be a narrow i.e. close to zero in z BB trigger for collision events, and a wider but with scaledown for background events.
------------------------------
Flemming Videbaek
Physics Department
Brookhaven National Laboratory
tlf: 631-344-4106
fax: 631-344-1334
videbaek@bnl.gov
This archive was generated by hypermail 2b29 : Mon Jul 03 2000 - 20:41:08 EDT