Dear shifter and potential shifter.
RHIC is presently in the process of improving luminosity by the combination of having the RF store
on as well as adding the beta(*). Each of these improvements can increase our effective data rate, and it is important
for the overall program this gets developed. It also mean that the 'conditions' for when to voting for store will change with time
The 'rules' as implemented presently are given below.
Very long store with low rates are not good for the experiment, as a store with bad characteristics such as wide vertex,
therefore we should vote to have such store aborted by RHIC. In those cases the machine also has a much shorter turn-around time
than following 'unplanned' aborts.
Guideline for deciding to 'vote for dump' and agreeing to dump.
1. ZDC(rate)< N/sec ==>dump
Since RHIC is getting better at getting stores back following a voluntary dump one should not let the store run to long.
- Note this is a rule that depends on where RHIC is in machine development.
At present 9/28 they should be able to get up to 300-400 initially thus
an N of ~100 is cause of dump.
- With the beta(*) going from 5->2 the rate should go up by another factor
of 2.5 and thus the dump criteria should go to N~250.
o 2 .ZDC(rate) has dropped to less than ~1/3 of initial value.
As the vertex gets wider, as well as having more de-bunched beam in store, the beam quality.
o No store should last more than 4 hours
Unless we are in the middle of something "special".
This rule is secondary to the other two rules.
If asked whether to vote for end-of-store do pay consideration on on-going activity
e.g. if studies are being made of if a run needs to get to a reasonable length ( >= 50K events).
Beam Quality
If background rate relative to beam are very large consult with MCR
(Blue /Yellow Ions ~ 20K ZDC singles rate should be ~6-8 K at most.
If the storage RF is supposed to be on, watch the beam-vertex, to check the actual width. It does happen that one or both beams de-bunched,
If this happen please call MCR and tell them our preference is to get a new store.
------------------------------------------------------
Flemming Videbaek
Physics Department
Brookhaven National Laboratory
tlf: 631-344-4106
fax 631-344-1334
e-mail: videbaek@bnl.gov
This archive was generated by hypermail 2b30 : Sat Sep 29 2001 - 09:46:23 EDT