# Presentation: 532054

## Relative Luminosity Analysis from PHENIX

- RIKEN BNL Research Center
- KAWABATA TAKAHIRO

## Instruments

- NTCS

- NTCN

- BBCN

**       ****GL1P scaler**
-  - crossing-by-crossing scalers       for 120 crossings        (60 crossings in run 2)  - live time only
-  - consists of 4 channels
-    M.B. (BBCLL1NTCwide )
-    NTCnarrow  / BBCLL1 / ZDC (N&S)

- Luminosity monitors
- BBCLL1 (|Z| < 75 cm)
- NTCwide
- NTCnarrow (|Z| < 40 cm)
- ZDC

## Relative luminosity

- no critical item for *A**N* measurement in run-2
- important for *A**LL* measurement in run-3
- 10–4 level precision required for sub-% level asymmetry measurement
- normalization in the cross section measurement stability of each luminosity monitor ?
- which is the best ?

## Scaler Counts

- GL1P counts vs Crossing number  - #10 and #30 ... large emittance  - #15-19  ... abort gap (Yellow)  - #55-59  ... abort gap (Blue)
- Only NTC counts beam-gas events.
- ZDC has low statistics.

## Specific Luminosity

- Normalized and plotted as     a  function of crossing number
- Specific luminosity fluctuates by 2-5%.
- NTCn is less stable. - only NTC counts beam-gas events.
- ZDC has low statistics.

## Systematic Error on Relative Luminosity

-  - Shown with the statistical errors                                by solid circles and lines.
- Evaluate*          * for random classification. -  All bunches were randomly sorted                                             into Group A and B. -  Repeat the calculation 400 times.
-  -  Shown by shaded area.
- Systematic error has fill dependence. -  ~0.3% for good fill. -  Improve by adding all fills up to ~0.2%.

## Time Dependence

- Spin relative luminosity RXY is plotted as a function of time. - solid lines .. Statistical error - shaded region          .. Systematic + Statistical
- Each point shows 10,000-sec time slot.
- Background colors indicate fills.
- RXY has a fill dependence.

- Time (DD/MM)

- RZDC/BBC

- RBBC/NTCn

## Correlation between Specific Luminosities

- Fluctuation of spe. lumi. is not important.
- Systematic errors depend on widths of loci.

## Dependence on Z-vertex width

- Differences in specific luminosities are plotted as a function of the Z-vertex wdith.
- Dependence on Z-vertex width is not clear.
- Bunch selection by Z-vertex width did not work well.

**Notes:**
Z-vertex can make differences between detectors and can be an origin of the systematic errors. I plotted the differences in specific luminosity between GL1P channels as a function of Z-vertex width. You can see the some correlations with the z-vertex width but it is not clear. If you perform the tight cut in z-vertex width, the systematic errors on relative luminosity will not improve.

## Bunch Selection

- Several bunches with the bad spe. lumi.                                                                                      are excluded   - shaded region .... before the selection   - black line .... after the selection   - red line ... statistical error   - solid circle ... RXY
- Bunch sel. slightly improves bad fills,                                    but not good fills.
- Results on RXY are ....   - NTCn/M.B.	...	1.0005  0.10%   - BBC/M.B.	...	0.9974  0.36%   - ZDC/M.B.	...	0.9981  0.37%   - BBC/NTCn	...	0.9969  0.41%   - ZDC/NTCn	...	0.9975  0.44%   - ZDC/BBC	...	1.0007  0.15%            by summing up Run40117-40655.

- Fill Number

- RZDC/BBC

- RBBC/NTCn

## Summary

- GL1P data from PHENIX were analyzed for relative luminosity study.
- Systematic error has a fill dependence.   - ~0.3% for good fill,      0.15% for Run40117-40655   - Small dependence on Z-vertex width   - Slightly improved by bunch selection
- Procedure for fill diagnosis should be established.