# Presentation: 824722

## RHIC CNI polarimeterRun-03 (Nearly) final results 

- Osamu Jinnouchi (RIKEN BNL Research Center)
***RHIC-Spin-Collaboration Meeting ***
***Jan. 22, 2004***

## Calibrations/Corrections in offline analysis

- Constrained and unconstrained variables of Carbon events
- Time
- Scale (fixed) – WFD clock
- Time zero – Unconstrained
- Energy
- Scale (fixed) – Am calibration (a few % uncertainty)
- Shift by Si dead layer – Unconstrained
- T0, d-layer can be determined by the fit to Carbon locus
- d-layer correction needs to be implemented in non-linear function of deposit energy (was linear at online analysis)
- d-layer estimation is very important, it directly couples to *–t, *hence it changes the AN
- These parameters are different by strip to strip, and time to time

- O.Jinnouchi @ RSC

- Jan. 22, 2004

## Fit to Carbon locus

- Fits with non-relative kinematics
- With the factor 1181.6, the fit is forced to the Carbon mass (11.17GeV/c2)
- t0 and d-layer are strongly correlated. Thus, it would be useful to see run-by-run stability, even though they can be simultaneously determined from fit.

- 20g/cm2

- 60g/cm2

- 100g/cm2

- O.Jinnouchi @ RSC

- Jan. 22, 2004

## Invariant mass (Carbon & alpha peaks)

*Invariant mass (Carbon & alpha peaks)*

- Carbon events are selected with the cut defined by invariant mass
- Back ground contribution can be estimated by changing the cut criteria (2, 3,...)
- Better separation is obtained than the fixed time window which was used in online

- 3cut

- Short bunch length
- RF cavity ON

- Short bunch length
- RF cavity OFF

- O.Jinnouchi @ RSC

- Jan. 22, 2004

## Run by run fluctuations (RF timing, beam position)

- Timing (arriving time) of the carbon banana is stable (as long as the RF and beam position are stable)
- However there were fluctuations when scanned through the whole run
- Once determined the T0 and D-layer at reference run, T0 could be fixed for any run as the deviation from the reference
- Only the d-layer is left as a free parameter

- BL

- YL

- Injections
- (red points)

- Flattop
- (blue points)

- O.Jinnouchi @ RSC

- Jan. 22, 2004

## Si dead-layer corrections 

- Widths are 50-80ug/cm2 in average
- Size of the fluctuations is ±5g/cm2 which is about the same uncertainty of Run-02
- Averaged value during the runs is determined for each silicon (not each strip)

- Good case

- Bad case

- Red: Injection

- Blue: flattop

*Projection*

-  ~ 5g/cm2

- Si strip #

- Si strip #

- BL

- YL

- O.Jinnouchi @ RSC

- Jan. 22, 2004

## Energy spectrums after the energy corrections

- The spectrums are shifted to higher energies due to the large dead layer correction
- The asymmetries (=) got almost nothing or small change, while the analyzing power (=AN) became smaller  indicating larger polarization with about 10% (relatively) increase

**YELLOW**

**BLUE**

- 2x 90 degree Si

- 4x 45 degree Si

- 2x 90 degree Si

- 4x 45 degree Si

- O.Jinnouchi @ RSC

- Jan. 22, 2004

## Revised analyzing power

*Revised analyzing power*

- Online results were based on the wrong AN(red curve)
- AN for the given run is calculated with weighted sum of this curve
- Increasing by about 10% in AN implies the reduction of polarization result by 10%

- Online 2003

- Larry’s fit to E950

- E950 data points

- O.Jinnouchi @ RSC

- Jan. 22, 2004

## Outlook

- From the first glance, the new numbers are more or less the same with the online values (-10% from AN, +10% from d-layer correction)
- New polarization values are ready to be released when the systematic errors become available
- Things to be done
- Understand the fluctuations in d-layer fit result
- Compare the d-layer size with Kyoto tandem test result
- Bunch by bunch study has not been done – new polarization values should include (customized) to each experiment

- O.Jinnouchi @ RSC

- Jan. 22, 2004

## Appendix slides ...

- O.Jinnouchi @ RSC

- Jan. 22, 2004

## AN for different energies

- L.Trueman’s  prediction based on pomeron model
- Assuming the 100GeV, 24GeV shape (Run-02 data points) as inputs

- O.Jinnouchi @ RSC

- Jan. 22, 2004

## Dead layer distribution at Run-02

- Silicons from the same wafer showed  quite similar values
- Known within 5g/cm2

- O.Jinnouchi @ RSC

- Jan. 22, 2004