1. BaBar IFR Upgrade
Mark Convery
SLAC
7 Jun 06

2. BaBar Muon System History
BaBar Instrumented Flux Return (IFR) designed to identify muons and neutral hadrons
Originally consisted of iron absorber plates interleaved with Resistive Plate Chambers (RPC’s)
Performance had been degrading since the start of BaBar in 1999 due to deteriorating performance of RPC’s
Remediation has been in three steps
Replacement of Forward Endcap with RPC’s in 2002
Replacement of two sextants of the Barrel with LST’s in 2004
Replacement of remaining four Barrel sextants planned for 2006
7 June 06
BaBar IFR Upgrade

3. Limited Streamer Tube Intro
LST’s are simple and robust wire chambers
Resistive cathode formed by extruded plastic comb coated with graphite
Anode wire at 5.5kV
Detectors mass-produced by existing Italian company
Phi-position given by struck wire
Z-position by signal induced on external strip plane
7 June 06
BaBar IFR Upgrade

4. 2004 Installation
Installation of 12 layers of LST’s and 6 layers of brass absorber
Top and bottom sextants completed in ‘04
4 side sextants to be completed ‘06
QC during and after production, and after installation critical to good performance
7 June 06
BaBar IFR Upgrade

5. LST Occupancy Plots
Online monitoring gives continuous check of electronics performance
<0.5% dead channels
7 June 06
BaBar IFR Upgrade

6. LST Single Layer Efficiencies
Offline monitoring of single layer efficiencies shows no
degradation in performance in the first year of operation
time
time
7 June 06
BaBar IFR Upgrade

7. LST Operational Issues
First two sextants of LST’s are “operational” and require very little operator intervention
A few issues found (and fixed) in the first year of running:
Flaky enable panel
Bad Isobutane
HV supply communication
Leaky C02 dewar
Total lost time<10 hours
Mature BaBar experiement has very high standards!
7 June 06
BaBar IFR Upgrade

8. Muon-ID Performance
Muon-ID perfomance in LST-sextants is now better than RPC’s were in 2000
Much better than current RPC performance
7 June 06
BaBar IFR Upgrade

9. 2006 LST Detector Hardware In tests at SLAC In Italy All LST modules
All Z-planes
All HV supplies
All HV cables
Most of the manpower comes from collaborating institutions (students, post-docs)
In Italy
Front-end electronics
Signal cables
7 June 06
BaBar IFR Upgrade

10. 2006 Mechanical Installation
Installation of side sextants will be more difficult than flat ones
Large number of fixtures and procedures have been defined and tested
7 June 06
BaBar IFR Upgrade

11. 2006 Installation Schedule
Shutdown begins August 21 to coincide with LCLS and PEP-II work
Re-start on January 5, 2007
Very tight schedule for LST installation
Much effort going into planning and reducing required time
Believe schedule is achievable, but very little schedule float
7 June 06
BaBar IFR Upgrade

12. Conclusion
Success with first two sextants indicates that LST’s will “fix” the muon-ID problem and BaBar will have a well-performing muon system for the remaining data to be taken
Very tight schedule for 2006 installation requires very careful planning to be successful
7 June 06
BaBar IFR Upgrade

13. 7 June 06
BaBar IFR Upgrade