# Presentation: 708866

## Cathode Strip Chamber Hits in the Cavern Background Samples

- David Adams
- Brookhaven National Laboratory
- March 9, 2007

- Cavern and Pileup Background Meeting

*Updated March 3, 2007 11:30 EST*

## Introduction

- CSC validation suite was used to study background samples
- Hit validation record all hits that cross a CSC wire plane
- Used here
- Modified to write hits from all PDG ID’s
- Formerly limited to muons
- Cluster validation records all found clusters
- Results reported at last validation meeting
- Different sample
- RDO is not yet available for the new cavern sample
- Data
- Cavern HITS dataset
- misal1_csc11.007904.cavernbg_sf10.simul.HITS.v12003105
- Seven files (1750 events) available at BNL

- Event Data History           David Adams   BNL

- December 2001

## Results

- Total of 6362 hits
- 3.6 hits/event
- 1139 events with hits
- 5.6 hit/event in these
- Various particle types
- See table

| PDGID | # hits | Frac |  | Frac |
| --- | --- | --- | --- | --- |
| none | 2129 | 0.33 | PDGLO | 0.60 |
| electron | 1527 | 0.24 |  |  |
| positron | 209 | 0.03 |  |  |
| muon | 1790 | 0.28 | PDGHI | 0.40 |
| proton | 639 | 0.10 |  |  |
| pion | 68 | 0.01 |  |  |

- Event Data History           David Adams   BNL

- December 2001

## Particle pT

*PDGLO*

*PDGHI*

*    **1             10           100         1000 MeV/c*

- Event Data History           David Adams   BNL

- December 2001

## Rates

- Sensitive area of detectors
- A = 2*4*8*(110 cm)*(80 cm) + 2*4*8*(110 cm)*(52 cm)
-         = 930 kcm2
- Hit rate at L = 1034/cm2/sec
- R = (3.6 hits/event)*(23 event/xing)/(25 ns/xing)/10
-         = 330 MHz
- Flux
- R/A = (330 MHz)/(930 kcm2)
-             = 0.36 kHz/cm2
- This is reasonable: nominal value is 1 KHz/cm2 at the inner part of the CSC.

*Safety factor*

- Event Data History           David Adams   BNL

- December 2001

## Chamber hit positions

*PDGHI*

*PDGLO*

*eta*

*phi*

- Event Data History           David Adams   BNL

- December 2001

## Chamber eta position

*High pT tracks favor large eta*

- Event Data History           David Adams   BNL

- December 2001

## Chamber phi position

- Event Data History           David Adams   BNL

- December 2001

## Hit time (ns)

- Event Data History           David Adams   BNL

- December 2001

## High pT contribution

- The cavern sample has a large high pT component
- Muon/proton/pion with pT=0.1-1.0 GeV/c
- Rate similar to minbias (see table below)
- Time and z distributions look like minbias
- We are double counting muons
- Pileup production includes both cavern and minbis
- Especially important if SF is applied
- Muon BG has correlated hits

|  | Muon hits/evt | PDG=0 hits/evt |
| --- | --- | --- |
| Cavern (w/o SF) | 0.10 | 0.12 |
| Minbias | 0.16 | 0.09 |

- Event Data History           David Adams   BNL

- December 2001

## Station multiplicities

*-CSL*

*+CSS*

*+CSL*

*-CSL*

*eta<0*

*eta>0*

- Event Data History           David Adams   BNL

- December 2001

## Phi sector multiplicities

- Event Data History           David Adams   BNL

- December 2001

## Eta asymmetry

- Define asymmetry
- A = (N+-N-)/(N++N-)
- dA = C/sqrt(N++N-)
- Correction C is 1.0 if
- A is close to zero
- Hits are independent
- For high pT, tracks go though chamber (4 layers)
- Set C = sqrt(4) = 2.0
- For low pT, set C= 1.0
- Underestimate—how bad?
- Table on following page show asymmetries

- Event Data History           David Adams   BNL

- December 2001

## Eta asymmetry (cont)

|  | C | N-/N+ | A | dA | A/dA |
| --- | --- | --- | --- | --- | --- |
| PDGLO | 1 | 2019/1846 | -0.045 | 0.016 | -2.8 |
| PDGID = 0 | 1 | 1070/1059 | -0.005 | 0.022 | -0.2 |
| electron | 1 | 849/678 | -0.112 | 0.026 | -4.4 |
| positron | 1 | 100/109 | +0.043 | 0.069 | +0.6 |
| PDGHI | 2 | 1304/1193 | -0.044 | 0.040 | -1.1 |
| mu- | 2 | 454/411 | 0.050 | 0.068 | -0.7 |
| mu+ | 2 | 491/434 | -0.062 | 0.066 | -0.9 |

- Event Data History           David Adams   BNL

- December 2001

## Conclusions

- Asymmetry for hi-pT particles is not significant
- A/dA = -1.1
- Low pT asymmetry may be significant
- A/dA = -2.8
- Look again when more data is available
- Assuming no correlations
- Major contribution from electrons (not PDGID=0)
- Could this be due to focusing of electrons in the toroidal field?
- Electrons from center deflect inward on one end and outward on the other
- Flux is consistent with expectation
- Cavern appears to include minbias muons
- Implies pileup production is double counting muons

- Event Data History           David Adams   BNL

- December 2001