# Presentation: 590953

## The                   Resistive Plate Chamber Forward Upgrades 

- The                   Resistive Plate Chamber Forward Upgrades

- Andrew Glenn
- University of Colorado, Boulder
- for the PHENIX Collaboration
- 23rd WWND Feb 14, 2007

_**Outline**_
- Motivation / Measurement Method
- Trigger Needs
- Instrumentation
- Trigger Details
- Offline Analysis Challenges

## Motivation

- The sea quark polarizations of the proton can be probed through the single spin asymmetry, AL, of the W+ and W-
- The PHENIX collaboration plans to determine AL and σ for W+ and W- bosons at forward and backward rapidities in p+p collisions at 500 GeV.
- In a p+p collision, two quarks will interact at two Bjorken momentum fractions (x1 and x2) and produce a W boson.
- PHENIX will look at the cases where the W decays to a muon and a neutrino.  It will be able to detect the muons but not the neutrino.

- A.M. Glenn 23rd WWND

## Method Details

- Using the number of muons detected at forward and backward rapidities, AL can be calculated using:
- We could simply compare AL to models but, the sea quark polarizations of the proton can be probed to first order through AL using:

- Large x1

- Large x1

- Large x2

- Large x2

- A.M. Glenn 23rd WWND

## Sensitivity

- In *Bunce et al, Prospects for Spin Physics at RHIC, Annu. Rev. Nucl. Part. Sci. 2000*, the sensitivity to the sea quark polarizations were calculated.
- The sensitivity is calculated from the number of muons detected as a function x1 and x2.
- The *Bunce et al. *paper*, **assumes* the pT of the W is zero which allows for a one-to-one correlation between measured μ kinematics and  the true W kinematics.

- A.M. Glenn 23rd WWND

## Because the neutrino can not be detected, the momentum of the W can not be completely reconstructed from the decay products causing a smearing in the momentum calculated for the W.
Plotting the true x1 value produced in PYTHIA versus the x1 value that would be calculated from the muon, a smearing occurs in the correlation.

- Plotting the true x1 value produced in PYTHIA versus the x1 value that would be calculated from the muon, a smearing occurs in the correlation.

- Smearing from W pT

- x calculated using  

- x from PYTHIA

- We will continue to study other effects such as going beyond leading order, reconstruction resolutions ...

- A.M. Glenn 23rd WWND

## PHENIX Trigger Needs

- NSF Funded
- Much of the manpower is DOE funded

- _Design Luminosity_
- √s = 500 GeV  σ=60mb
-    L = 2x1032/cm2/s

- Total X-sec rate=12MHz

- DAQ LIMIT
- =1-2kHz(forμarm)

- Required RF
- ~ 10,000

- Abilene Christian University, Brookhaven National Laboratory, University of California, Riverside, CIAE, University of Colorado, Columbia University/Nevis Laboratory, Georgia State University, University of Illinois, Iowa State University, Korea University, Muhlenberg College, Peking University

- Current MuID LL1has a RF of ~500 at 200GeV

- A.M. Glenn 23rd WWND

## Trigger should provide momentum selection and vertex pointing

- RPC 3S

- RPC 2S

- RPC 1(a,b)S

- RPC 3N

- RPC 2N

- RPC 1(a,b)N

- ST1

- ST2

- ST3

- A.M. Glenn 23rd WWND

## Resistive Plate Chambers

- Good timing performance (~ 1-2 ns)
- Good rate capability (~several kHz/cm2)
- Space resolution (~ *cm* )
- Simple design & low cost

- WE ARE COPYING CMS

- Typical gas mixture: 95%R134A  + 4.5% ISO + 0.5% SF6

- 0.5cm strips

- Gas

- Gas

- A.M. Glenn 23rd WWND

## Developing Local Expertise

- Test Stands at multiple institutions

- GSU Built RPCs

- A.M. Glenn 23rd WWND

## Test Stand Results

- 0.5cm strips

- Strips widths smaller than ~1cm are useless without ADC
- No $$ or plans for ADC (with more than one bit)
- Cluster distributions needed for trigger simulations

- ~5400ft elevation

- A.M. Glenn 23rd WWND

## Detector Geometry

- RPC2 North

- RPC3 North

- MuTR backplate

- “Rings” of equal  coverage

- Accessible from tunnel

- Match MuTRdead areas

- A.M. Glenn 23rd WWND

## Readout Strip Geometry

| RPC2 |
| --- |
| strips: 467.9 x 60.5 (64) |
| strips: 441.0 x 60.5 (58) |
| strips: 418.2 x 48.8 (64) |
| strips: 298.9 x 48.8 (57) |
| strips: 382.7 x 38.2 (64) |
| strips: 369.1 x 38.2 (56) |
| strips: 357.8 x 28.4 (64) |
| strips: 354.7 x 28.4  (54) |

- Units of mm (channels)

- Octant and strip readout to be designed to complement MuTR

|  | RPC1 a+b | RPC2 | RPC3 |
| --- | --- | --- | --- |
| Channels | 3072 | 3848 | 2872 |

**RPC2 Octant**

*141.0 x 11.4 mm *Inner RPC1
- to
*554.2 x 64.6 mm *Outer RPC3

- A.M. Glenn 23rd WWND

## MuTR FEE Upgrade

- Current MuTR Front End Electronics are too slow for Level 1 trigger
- New FEE will provide list of hit strips to Level 1 trigger
- Current plan is to instrument non-stereo plains in MuTR stations 1 and 2 for both arms
- Funding approved by JSPS

***Riken-BNL Research Center, ******University of Kyoto,***
***Rikkyo University,  KEK, ******Los Alamos National Lab, ******University of New Mexico***

- A.M. Glenn 23rd WWND

## MuTr FEE Modifications

- A.M. Glenn 23rd WWND

## Trigger Algorithm

- Candidates found by matching RPC1/2 hits within angular range. Momentum cut made by matching hit in MuTr station 2 within three cathode strips of RPC projection.

**or**
**RPC1(a+b)**

**RPC2**

- A.M. Glenn 23rd WWND

## Trigger Simulation Results

- Full GEANT simulation of PYTHIA events
- Use several variations of trigger algorithms (detector combinations) to rejection factors

- Good efficiency for high pT muons
- Based on ~1M PYTHIA p+p events at √s = 500GeV.
- Rejection factors are combined for both muon arms.
- USES SLIGHTLY DIFFERENT PAD READOUT
**All over the rejection goal of 10,000**

| 
RPC1/2 Angle Cut: | MuRPC+ST2
|strip|<=3
NO CLUSTERS | MuRPC+ST2
|strip|<=3
CLUSTERS | MuRPC+ST1+ST2
|strip|<=3
(RPC1->ST1) |
| --- | --- | --- | --- |
| 3 degree cut  | 14,672 (1,780) | 14,459 (1,740) | 13,127 (1,506) |

- (Statistical errors shown in parenthesis.)

- A.M. Glenn 23rd WWND

## Beam-Background Rejection

**Severity of beam backgrounds at 500GeV (with high luminosity) is  largely unknown. **
**RPC timing used to eliminate early-time hits.**
**Trigger rejection largely independent of beam-related backgrounds.  **

**Collisions!**

**Beam-Related Background**

- A.M. Glenn 23rd WWND

## Time Line

|  | Summer 2007 | Summer 2008 | Summer 2009 | Pre RHIC II |
| --- | --- | --- | --- | --- |
| RPCs |  | RPC 3
North & South | RPC 2
North & South | RPC 1a,b |
| MuTR FEE | 2 Octants of Stations 1+2
South | All of  Stations 1+2South | All of  Stations 1+2North |  |

- Absorber may be added in RPC1’s position matching MuTR FEE coverage/timetable.
- If so, it will be removed or reduced prior to installation in RPC1 a,b

- A.M. Glenn 23rd WWND

## Offline Backgrounds

- Triggering on W events is necessary but not sufficient. We should try to address all of the offline background issues we can before taking data
**Punch through**: Small fraction of high pT hadrons which penetrate through the detector
**Fake High p****T**: Small fraction of low pT hadrons which decay in the MuTR and are incorectly reconstructed with high pT

- A.M. Glenn 23rd WWND

## Punch through

- Red line is UA1 fit form.
- Magnta & Black: PYTHIA  at midrapidity.
- Blue: PYTHIA at forward rapidity (eta 1.2-2.2).

- Applying tight matching cuts substantially
- reduces the background for pions (and kaons)
- except irreducible fully penetrating category.
-                          10M input    10GeV        20GeV
- z!=0 background  	           45k  6k   62k  7k
- z=0 true punch through        1k  1k     1k  1k
- z=0 punch + shower           11k  3k     9k  2k

- Punch through should not be a major issue especially if any absorber is added

- A.M. Glenn 23rd WWND

## Fake High pT

- Fake High pT

- Hadron decays in the MuTR can make tracks appear straighter

- High pT track

- Can be battled with:
- Tighter quality cuts / and inter detector matching
- Additional absorber (Tungsten from Nose Cone Calorimeter ...)
- Additional detectors (Forward Silicon Vertex detector)

- A.M. Glenn 23rd WWND

## Summary

- The polarized proton program at RHIC will address two key missing pieces of information through *W*+/- production:
- The antiquark spin structure functions
- The PHENIX Forward Upgrade will provide the event selection necessary to access this physics:
- New RPC-based tracking chambers
- New electronics for MuTr LL1 input
- New Level-1 Muon Trigger electronics

- A.M. Glenn 23rd WWND

## Side Note on Heavy Ions

- RPCs may provide some reduction of combinatoric background in heavy ion collisions, but the pad sizes are too large to have a dramatic impact
- Studies are under way to see if the RPCs can help trigger on dimuons in A+A collisions at RHIC II.

- A.M. Glenn 23rd WWND

- EXTRAS

- A.M. Glenn 23rd WWND

- A.M. Glenn 23rd WWND

- Assuming pT of W =0

- A.M. Glenn 23rd WWND

******f(x, μ****2****)** :The probability of finding a certain parton type (f = u, u, d, d, . . . , g) with positive helicity in a nucleon of positive helicity, minus the probability for finding it with negative helicity

- Superscripts refer to partons and subscripts to the parent hadron.

- A.M. Glenn 23rd WWND

##   Physics Timeline

**2005            2006            2007           2008            2009               ....        2012 (RHIC II)**

**       ****10 pb****-1****   .......................................... ********275pb****-1         ****             ........    950pb****-1**

**√****s= .............................  200 GeV  ..............................   500 GeV|**

** ****P= 0.5               0.6              0.7  ..........................................**

**Inclusive hadrons + Jets**
** ****~ 25%   Transverse Physics**
**                    ****Charm Physics**
**                                                        ****direct photons**
**                                                        ****bottom physics**
**                                                                                                     ****W-physics**

***A******LL******(hadrons, Jets)***

***A******LL******(charm****)*

***A******LL******(******γ******)***

***A******L******(******W****)*

** ****L= 1x10****31****cm****-2****s****-1****                                                        6x10****31****cm****-2****s****-1  ****        1.6x10****32****cm****-2****s****-1**

-  see Spin report to DOE http://spin.riken.bnl.gov/rsc/

- @ 200GeV

- @ 500GeV

- A.M. Glenn 23rd WWND

## RPC dimensions

|  |  | RPC1a |  | RPC1b |  | RPC2 |  | RPC3 |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | theta (deg) | Radius | width | radius | width | radius | width | radius | width |
| possible |  |  |  |  |  | 5280.2 |  | 5231.7 |  |
|  | 34.36 | 933.2 | 773.1 | 1016.8 | 842.3 | 4675.4 | 3873.2 |  |  |
| ring 8 |  | strips: 181.4 x 12.1 (64) |  |  strips: 197.7 x 13.2 (64) |  | strips: 467.9 x 60.5 (64) |  |  |  |
|  | 31.60 |  |  |  |  | 4207.5 | 3485.6 |  |  |
| ring 7 |  |  |  |  |  | strips: 441.0 x 60.5 (58) |  |  |  |
|  | 28.84 | 751.8 | 622.8 | 819.1 | 678.6 | 3766.5 | 2120.3 | 4991.4 | 4135.0 |
| ring 6 |  | strips: 164.3 x 9.7 (64) |  | strips: 177.7 x 10.6 (64) |  | strips: 418.2 x 48.8 (64) |  | strips: 554.2 x 64.6 (64) |  |
|  | 26.09 |  |  |  |  | 3348.3 | 2773.9 | 4437.2 | 3675.9 |
| ring 5 |  |  |  |  |  | strips: 298.9 x 48.8 (57) |  | strips: 528.6 x 64.6 (57) |  |
|  | 23.33 | 588.7 | 487.7 | 641.4 | 531.4 | 2949.4 | 2443.4 | 3908.6 | 3238.0 |
| ring 4 |  | strips: 151.1 x 15.2 (32) |  | strips: 163.5 x 16.6 (32) |  | strips: 382.7 x 38.2 (64) |  | strips: 507.1 x 50.6 (64) |  |
|  | 20.57 |  |  |  |  | 22566.8 | 2126.4 | 3401.5 | 2817.9 |
| ring 3 |  |  |  |  |  | strips: 369.1 x 38.2 (56) |  | strips: 493.3 x 50.6 (56) |  |
|  | 17.81 | 438.7 | 363.4 | 477.9 | 395.9 | 2197.7 | 1820.6 | 2912.3 | 2412.7 |
| ring2 |  | strips: 141.0 x 11.4 (32) |  | strips: 153.6 x 12.4 (32) |  | strips: 357.8 x 28.4 (64) |  | strips: 474.2 x 37.7 (64) |  |
|  | 15.06 |  |  |  |  | 1839.8 | 1524.2 | 2438.1 | 2019.8 |
| ring1 |  |  |  |  |  | strips: 3548.7 x 28.4  (54) |  | strips: 462.1 x 37.7 (54) |  |
|  | 12.30 | 297.6 | 246.6 | 324.3 | 268.6 | 1491.1 | 1235.3 | 1976.1 | 1637.0 |
| possible |  |  |  |  |  | 1468.4 |  | 1926.4 |  |
|  |  | split gap: ring 4 and 5 |  | split gaps: ring 2 and 3 + ring 6.and 7  |  | no split gaps |  | no split gaps |  |

- all units in mm (except theta)

- strip length and width consider full acceptance in theta and phi in the octants (i.e. no loss due to readout and boxes)strip widths are determined at the outer radius of two paired rings

- A.M. Glenn 23rd WWND

## Trigger Rate and Rejection

**HQ signal **

- ___ __momentum dist. At vs=200 GeV_

**50**

**25**

**Momentum GeV/c**

**P****T****>10GeV/c**

**P****T****>20GeV/c**

**W signal **

- REAL DATA

- Need Momentum Selectivity in the LVL-1 Trigger!

- A.M. Glenn 23rd WWND

## Existing MuID Level-1 Trigger

- Logical tubes formed by OR of physical tubes across panels in each gap.

- The most probable trajectory for a vertex muon striking a gap-1 logical tube is to continue on a path of equal *dx/dz* (vertical tubes) or *dy/dz* (horizontal tubes). Tubes w/ the same *dx/dz* (or *dy/dz*) get the same index.

**Rejection Factor ~500 @ 200 GeV/c**

- A.M. Glenn 23rd WWND