# Presentation: 295196

## Final   Result from RHIC pC CNI

- Osamu Jinnouchi (RIKEN BNL Research Center)
***RHIC-Spin-Collaboration Meeting ***
***Mar. 19, 2004***

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## Towards the final result

- Goal/Aim of this work
- Provide the stable, reliable polarization info with properly estimated systematic errors
- Understand the origin of the systematic errors, correct them if possible
- Advances of Run-03 data from Run-02
- In Run-02, Systematic error was estimated with run-by-run fluctuations and bunch shuffling because of the limited info
-     (scaler data – phenomenological approach)
- In Run-03, event-by-event data enables further detailed study

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Radial polarization component was observed throughout the run
The shape of –t dependence indicated a non-CNI origin
     (Similar flat –t dependence was also seen in yellow flattop) 

- The shape of *–t* dependence indicated a non-CNI origin
-      (Similar flat *–t* dependence was also seen in yellow flattop)

*Issues known during the Run-03 (radial component) *

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Issues known during the Run-03 (Cross asymmetry) 

- Cross asymmetries were constantly observed throughout the run
- It meant that AN for the detectors were not balanced

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Consider each Si strip as an Individual Polarimeter

- Square-root-formula (X,Y,Cross,etc), 2-fit (-fit) always require a set of detectors to calculate asymmetry, and it is not easy to directly specify which detectors (strips) are bad and how much they are
- New diagnostic method is to use each Si-strip as an individual  polarimeter, but still keep the cancellation mechanism on acceptance and luminosity asymmetry
- Pi = (U(i) – R*D(i)) / (U(i) + R*D(i)) / AN(i)
-                                          U(i), D(i) : i-strip carbon counts
-                                      R =  U(i)/  D(i) : luminosity ratio
-                                      AN(i) : Analyzing power of i-strip
- Some results with Scaler data were shown last year, the following results were based on Event-mode data (with new calibration)

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Si dead-layer corrections 

- (Off-line procedures how to determine d-layer were shown in Jan.)
- Widths are distributed 50-80ug/cm2
- Size of the fluctuations is ±5g/cm2 which is about the same uncertainty of Run-02
- Averaged values for each Si (not each strip) were fixed and used for all the analysis
- Shifted energy spectrum by ~100keV, make AN smaller (~10%)

- Time zero is adjusted for each run, each strip, and the kinematical function is always on the Carbon mass peak
- AN fit E950 was revised  AN became larger (~10%)

**Si-1**

**Si-2**

**Si-3**

**Si-4**

**Si-5**

**Si-6**

**Si-1**

**Si-2**

**Si-3**

**Si-4**

**Si-5**

**Si-6**

- O.Jinnouchi @ RSC

- Mar. 19, 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

- Mar. 19, 2004

## Event selection with Carbon mass 

- Online event selection was defined by time window (±12nsec)
- By using the mass for event cut criteria, signal/noise ratio could be improved
- Mass resolution differs run by run, and also depending on the Carbon energy. These effects are taken into account

**45 ****degree detectors**

**90 ****degree detectors (Edge)**

- 11.17GeV

********

********

********

**Online WFD timing cut**

**3******** mass cut**

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Strip-by-Strip polarization (YELLOW)

- P(i) is calculated for each strip for different mass cut
- With the normalization, the flat distribution is expected
- For 45 degree detectors AN is reduced by 2
- Sign is flipped for left side detectors (Si4-6)
- The values are rather stable for different cuts

**YL Flattop (20days accumulated)**

**YL Injection (20days accumulated)**

**Si-1**

**Si-2**

**Si-3**

**Si-4**

**Si-5**

**Si-6**

**Si-1**

**Si-2**

**Si-3**

**Si-4**

**Si-5**

**Si-6**

**45**

**90**

**45**

**45**

**90**

**45**

**45**

**90**

**45**

**45**

**90**

**45**

** ****1.5********cut**
******cut**

**Strip Number**

**Strip Number**

**Polarization**

**Polarization**

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Strip-by-Strip polarization (Blue)

- The results are very unstable and there is strong correlation to the mass cut
- The values looks unreasonable for several detectors far beyond statistical uncertainty

**BL Flattop (20days accumulated)**

**BL Injection (20days accumulated)**

**Si-1**

**Si-2**

**Si-3**

**Si-4**

**Si-5**

**Si-6**

**Si-1**

**Si-2**

**Si-3**

**Si-4**

**Si-5**

**Si-6**

**45**

**90**

**45**

**45**

**90**

**45**

**45**

**90**

**45**

**45**

**90**

**45**

**Strip Number**

**Polarization**

**Strip Number**

**Polarization**

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Bunch (Spin) dependence of the carbon mass

- One particular strip in blue CNI sees extremely large difference btw plus/minus bunches
-     ( will be eliminated from all the analysis)
- Some strips (in blue CNI) see small but the same effect
- Obviously there is large fluctuation in regards to Carbon mass value (either T.o.f. or Energy is moving)

**BL**

**YL**

- M+– M–

- M+– M–

**(****see next page for zoomed plots)**

**0.1**

**-0.1**

**0.1**

**-0.1**

**GeV**

**GeV**

- Bunch Crossing

- GeV

- Mass Width
- Stable ~1.5GeV

- Mass Center -MC

**Strip Number**

**Strip Number**

- Should be excluded from analysis

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Zoom up of the previous page

**BL**

**YL**

**Positive Bunches**

**Negative Bunches**

**0.02****GeV**

**-0.02****GeV**

**0.02****GeV**

**-0.02****GeV**

- M+– M–

- M+– M–

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Comparison btw different mass cut (Yellow)

- Corrections on the mass peak improves the cut dependence
- There is small structures in the case of flattop which indicates the radial asymmetry component
- The edge strips (2 strips in both edge) in 90 degree detectors always behave differently, we decided to exclude them from polarization analysis

** ****1.0********cut**
******cut**
******cut**

**YL Flattop (20days accumulated)**

**YL Injection (20days accumulated)**

**Si-1**

**Si-2**

**Si-3**

**Si-4**

**Si-5**

**Si-6**

**Si-1**

**Si-2**

**Si-3**

**Si-4**

**Si-5**

**Si-6**

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Comparison btw different mass cut (Blue)

- In case of blue CNI, the improvements are much clear
- There are repetitive structures in flattop
- Two edge strips in 90o and the 1st strip of Si-3 should be neglected

** ****1.0********cut**
******cut**
******cut**

**BL Flattop (20days accumulated)**

**BL Injection (20days accumulated)**

**Si-1**

**Si-2**

**Si-3**

**Si-4**

**Si-5**

**Si-6**

**Si-1**

**Si-2**

**Si-3**

**Si-4**

**Si-5**

**Si-6**

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Statistical significance from different cut

- With the following formula, the statistical significance can be assessed (for the case, one data set is the subset of the other)
- Sig. = | 1 – 2 | / (2- 2 2)
- gauss=1 is expected for stat. only
- Excess could be considered as systematic errors
- sys =  2 – 1    x stat
- Yellow --- 0.5% (FL) 1.5% (IJ)
- BLUE  --- 1.1% (FL) 1.3% (IJ)
-                        in polarization

**Strip Number**

**Significance**

**significance**

- 2

- 4

- 6

- 8

- 10

- 2

- 4

- 6

- 8

- 10

- Yellow Flattop

- Red –  **+/-2******** to +/-3******

- Black –  **+/-2******** to +/-3******

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## -t dependence of the X/Y asymmetry (Yellow)

*-t dependence of the X/Y asymmetry (**Yellow**)*

- In yellow flattop, radial component is observed
- Cross asymmetry is around zero

- YL Injection

- YL Flattop

-  LeftRight

- 550keV

- 1050keV

-  UpDown

-  Cross

- 550keV

- 1050keV

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## -t dependence of the X/Y asymmetry (Blue)

*-t dependence of the X/Y asymmetry (Blue)*

- The radial component has *–t* dependence and the shape is similar to the vertical component
- The cross asymmetry is around zero

- BL Flattop

- BL Injection

- 550keV

- 1050keV

-  LeftRight

-  UpDown

-  Cross

- 550keV

- 1050keV

- The ratio of UpDown/LeftRight
- BL Flattop

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Systematic error estimations from two scenarios (Yellow Flattop)

- Try to fit with two assumptions
- Systematic error is estimated with
-  = (fit2 – 1) x stat
- Two edge strips are removed

- Vertical Pol. Only

- +/- 4% polarization error (out of 22%)

- Allow radial components

- +/- 1% polarization error (out of 23%)
- 12o toward inside of the ring

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Systematic error estimations from two scenarios (Blue Flattop)

- The systematic errors largely differ depending on the assumptions

- Vertical Pol. Only

- +/- 9% polarization error (out of 32%)

- Allow radial components

- +/- 3% polarization error (out of 34%)
- 17o toward inside of the ring

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Cases for injections 

- O.Jinnouchi @ RSC

- Mar. 19, 2004

## Summary

- Procedure has been established to stabilize the CNI measurements
- The major systematic error components are estimated
- Vertical only (Flattop)
- BL – 9% (out of 32%)
- YL – 4% (out of 22%)
- Allow radial (Flattop)
- BL – 3% (out of 34%)
- YL – 1% (out of 23%)
- Event selection dependence is small
- Applying the procedure is rather straightforward
- The run-by-run (fill by fill) results for experiments will be done soon
-      (including the bunch selection)

- O.Jinnouchi @ RSC

- Mar. 19, 2004