# Presentation: 879877

## Time of Flight System for the PHENIX high-pT Detector UpgradeJulia Velkovska (Vanderbilt) , for PHENIX

- Motivation for high-pt PID in PHENIX
- high-pt detector
- MRPC TOF in PHENIX
- Prototype runs
- Final design

- J.Velkovska       PANIC05

- 10/27/2005

## Physics motivation for the high-pT detector

- _[Phys. Rev. ](http://ojps.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000091000017172301000001&idtype=cvips&gifs=yes)__[Lett](http://ojps.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000091000017172301000001&idtype=cvips&gifs=yes)__[ 91, 172301](http://ojps.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000091000017172301000001&idtype=cvips&gifs=yes)__[ ](http://ojps.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000091000017172301000001&idtype=cvips&gifs=yes)__[(2003)](http://ojps.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000091000017172301000001&idtype=cvips&gifs=yes)_*.** *

- Large suppression of 
- Non-suppression of protons and anti-protons
- Large baryon/meson ratios, a factor of 3 above standard fragmentation
- “   The **large (anti)baryon to pion excess** relative to expectations from parton fragmentation functions remains **the most striking unpredicted experimental observation at RHIC**. The data clearly indicates that **a new mechanism** other than universal parton fragmentation is the dominant source of baryons and anti-baryons in the intermediate pT range in heavy ion collisions. “ *Phenix White paper*
- PID out to ~ 10 GeV needed !

- J.Velkovska       PANIC05

- 10/27/2005

## PID scheme with TOF, RICH and Aerogel

- System requirements for TOF:
- Resolution 100 ps
- Efficiency   > 95 %
- Occupancy < 10 %
- Total cost < 500k : MRPC TOF wins over scintillator TOF

- J.Velkovska       PANIC05

- 10/27/2005

## The high-pT detector in PHEINIX

- ACC installed in Run4 , Run5
- MRPC prototype tested in Run5
- Large area MRPC will be installed for Run6

- J.Velkovska       PANIC05

- 10/27/2005

## What is a MRPC ?

- J.Velkovska       PANIC05

- 10/27/2005

## PHENIX MRPC final design

- J.Velkovska       PANIC05

- 10/27/2005

## Here is how an early prototype looked:

- ...now the honeycomb is thinner, the spacers are the exact size,
-  the strips have slightly different dimensions, but the internal structure
- is the same

- J.Velkovska       PANIC05

- 10/27/2005

## 3 Prototypes tested at KEK in June 2004

-    PH1                           PH2                        PH3

_**Different pad/strip design, same structure inside**_
- PH1: 50.9 x 53.5 cm2, 32 strips, readout at both ends.
- PH2: 12.5 x 53.5 cm2, 8 strips, readout at both ends.
- PH3: 12.7 x 53.7 cm2, 48 pads (6x2 cm2), similar to STAR MRPC.

- J.Velkovska       PANIC05

- 10/27/2005

## KEK T1 beam line

**KEK T1 beam line**

- J.Velkovska       PANIC05

- 10/27/2005

## PH2

**PH2**

- efficiency

******T ****= 68 ps**
**(best value)**

- Streamer

- Avalanche

- +

- p

- J.Velkovska       PANIC05

- 10/27/2005

## KEK beam test results

- Time Resolution

- Efficiency

-  PH1: worse timing resolution (>150 ps), same efficency as PH2. Problem on uniformity
-            of  performance across the chamber. Difficulties in mechanical assembly.
-  PH2: **68ps timing resolution** at optimal condition,
-             but 90% efficiency. Solution  increase strip width.
-  PH3: comparable timing resolution with PH2 (best value: 67ps), 98% efficiency.

- Gas mixture:95%/5% r134a, iC4H10

- J.Velkovska       PANIC05

- 10/27/2005

## RUN5 goals

- To test TOF.W prototype in the PHENIX environment
- Test 3 prototypes for 3 months continuous operation in AA beam conditions
- Operate  the detector within PHENIX
- Check timing resolution and efficiency
- To test electronics chain ( pre-amp +FEMs)
- Can we use analog signal (only) from RICE pre-amp + TOF.E design FEMs and retain the timing resolution obtained in test beam at KEK

- J.Velkovska       PANIC05

- 10/27/2005

## RUN5 configuration: 2 boxes as shown 

- PH2 and PH3 previously tested. PH4 – wider strips – considered for final design

**PH4      PH4      PH3      PH2**

- J.Velkovska       PANIC05

- 10/27/2005

## RUN 5: MRPCs before installation

- 192 electronics channels instrumented
- To test digitization on-board vs digitization in the FEMs : both analog and digital signals were read-out from selected strips
- Digitization in FEMs desirable because:
- Proven technology (used since day1 in TOF-East)
- Less dissipated power at the detector – can operate with air cooling

- J.Velkovska       PANIC05

- 10/27/2005

## RUN 5 results : timing resolution

- Comparable performance in both read-out chains
- Resolution  for full start ( BBC) + stop (MRPC) ~ 100 ps
- Design goal for both detector and electronics is met !

- J.Velkovska       PANIC05

- 10/27/2005

## Final design:

- 1024 readout channels
- 128 MRPCs , 4 strips/each with double ended readout (detailed dimensions on slide 6)
- 4 gas volumes . Total active area ~ 8 m2
- Pre-amplification of signals at the detector
- Analog signal recorded in FEM ( to be used for slewing corrections). Digitization in FEM

- J.Velkovska       PANIC05

- 10/27/2005

## Final detector: mechanics

- Checkerboard pattern of MRPC+preamp electronics
- optimize active area
- Keep the electronics outside the box to limit noise
- Fit into 3” of radial space available in PHENIX West arm
- The most complicated part Vanderbilt machine shop has ever built

- J.Velkovska       PANIC05

- 10/27/2005

## Summary and status

- In the period Jan 2004 – Oct 2005 we have gone from conceptual ideas to final detector construction ( help from our STAR colleagues at RICE university is gratefully acknowledged).
- A complete detector + electronics chain was successfully operated within PHENIX for 3 months in heavy ion beam conditions in 2005. All design goals were met.
- Status today:
- All detector modules produced
- Extremely tight schedule for electronics production
- We expect to install at least half of the full system in 3 weeks
- I hope that my next talk will be about physics produced with the new TOF detector !

- J.Velkovska       PANIC05

- 10/27/2005