Notes on the procedure of spin flipper measurement in RHIC

Osamu Jinnouchi Dec. 2004

(This note is written based on the measurement condition till run-04, after run-05 the things might be changed due to the newly installed RHIC polarimeter application)

For this measurement, there is not so much things to be prepared for RHIC polarimeter side except for a few minor things

1. For this study a unique number (counter) for each RHIC bunch must be assigned in the RHIC polarimeter data. To activate this feature, a variable “RevolutionDelim” in configuration file required to be set as “1”. Note that before each measurement the configuration file “rhicpol.ini” is replaced (copied) with the already prepared initial files according to the data acquisition mode. In case of “event mode” (spin-flipper is taken with this mode), the file “rhicpol_at.ini” is used. From Run-05 default value of this variable would be 1, but it is recommended to confirm this before the spin-flipper commissioning.

2. The spin-flipper operation time is about a few second. It is better to take the data well before and well after of this flipper operation. The ideal time would be around 1min, and this will be about 2~3 times larger data samples than the regular measurements.

3. Basic procedure of this measurement is expected to be as same as the regular measurements, but the start/stop of the measurements should be manually. In Run-04, this forced stop (“STOP” command in the pet page) caused the problems of the overwriting on the existing data. The mechanism of this overwriting must be understood before Run-05. The overwriting itself is expected to be eliminated by the new RHIC application.

4. It is better to know the polarization values before and after this spin-flipper operation. The regular CNI measurements should be taken between.

The Procedure would be simply,

· Take regular run

· Take spin-flipper run

· Take regular run

· Take spin-flipper run

· ….. continue ….