a Stanford Linear Accelerator Center

b CEA-Saclay, c LPNHE des Universités Paris 6 et Paris 7d LAL, Universite Paris Sude Ecole Polytechnique, Laboratorire Leprince Ringuetf Lawrence Berkeley National Laboratoryg Colorado State Universityh University of Cincinnatii University of Tennessee

D ETECTION OF I NTERNALLY R EFLECTED C HERENKOV LIGHT

STATUS REPORTKalanand Mishra , University of Cincinnati

BaBar collaboration meeting - September 29th 2005

The BABAR-DIRC Collaboration

R. Andreassen,h N. Arnaud,d D. Aston,a N. van Bakel,a D. Bernard,e D.N. Brown,f J. Chauveau,c X. Giroux,d Ph. Grenier,e G. Grosdidier,d

T. Hadig,a G. Hamel de Monchenault,b A. Höcker,d M. John,c R.W. Kadel,f M. Legendre,b J. Libby,a A.-M. Lutz,d J. Malcles,c

G. Mancinelli,h B.T. Meadows,h K. Mishra,h D. Muller,a J. Ocariz,c M. Pripstein,f B.N. Ratcliff,a S. Schrenk,e J. Schwiening,a M.D. Sokoloff,h

S. Spanier,i K. Suzuki,a G. Therin,c Ch. Thiebaux,e G. Vasseur,b J. Va'vra,a R.J. Wilson,g G. Wormser,d A. Yarritu,a Q. Zeng,g M. Zitob

2

Overview

DIRC Safety Data Quality Fast Monitoring Operations DIRC Backgrounds DIRC Water Quality Spares Status Shutdown Plans Conclusion

3

DIRC Safety

DIRC Safety documents available on the web athttp://www.slac.stanford.edu/BFROOT/www/Detector/DIRC/DircOperations/safety.html

Additional safety requirements in light of the new Controlled Access guidelines. Modification of the routine worker JHAM to deal with this issue :

http://www.slac.stanford.edu/BFROOT/www/Detector/DIRC/Operations/DIRC-SysWork-JHAM.pdf

List of subsystem workers allowed to make Controlled Access:43 Arnaud Nicolas44 Mishra Kalanand45 McCulloch Matthew46 Salvati Emmanuele47 Va'vra Jaroslav

All of them are trained now.

DIRC Crew

4

Data Quality

• Run 5 data : good quality overall• Re-processing of Runs 1-4 going smoothly

- Problem with the new sector-by-sector rolling calibrations fixed

- Monitoring improved to detect problems (similar to the ones mentioned below) quicker• 4 hardware failures since the beginning of Run 5 :

- broken fan (5/29) 30 min down time

- failure of a HV board (7/10) 89 pb-1 bad data

- broken chiller component (9/13) 45’ down time

- FEE power supply failure (9/27) DIRC out of data- taking for a day

DIRC Crew

5

Fast Monitoring

JAS pages more user-friendly.

one plot per page with more precise explanations.

improved layout : each page has links to the previous & next plots for easy navigation.

Nicolas Arnaud

DIRC Fast Monitoring ( 1/5) :

Fast monitoring guidance Fast monitoring guidance improved :improved :

6

Operations (1/5)

May, 29: Fan failure ( 30’ DT)

- Shut down FEE crate in sector 2

- Status bypassed, crate running with 8/9 fans

- Replaced the fan tray during June 20-21 access

- Complete replacement scheduled (all sectors) in

October shutdown to avoid similar problems in future

Kalanand M

Nicolas A

Emmanuele S

Healthy fan

Dying fan

Alarm Level

7

Operations (2/5)

July, 10: For the first time ever, a HV board (in sector 1) died

- Problem clearly visible in DQM plots.

- Problem didn’t trigger red alarm but rather a permanent yellow alarm and scaler rate went ~ 0. Noticed after 3 hrs by pilot.

- Board replaced 2 hrs later with help from Jose ( owl shift ; at least 2 people needed to safely replace a HV board)

- 6 runs with ~ 3% DRC-acceptance off. Data declared unusable by DQG (89 pb-1).

- redefined alarm levels to protect against such failures.

Kalanand M

Nicolas A

Emmanuele S

Occupancy in Sector 1

TDC hits per group

8

Operations (3/5)

Sequence of events :-1:30 am: HV board 5, sec 1 fails- 4:36 am : DRC expert paged- 4:46 am : Problem understood,

decided to replace the board- 6:06 am : beam-lost inj./tune- 6:30 am : board replaced

- 6:36 am : stable beam

Lessons Learned:

- Fast monitoring layout improved to 'force' DQMs to look at occupancy plots per HV group;- low alarm levels added for scalers;- similar failure would now trigger a red alarm in the alarm handler.

Kalanand M

Nicolas A

Emmanuele S

9

Scaler rate, sector 3

7 am 8 am

Page

Switch to BCS

Back todata taking

Beam loss!

Injection

Chiller goes off

Operations (4/5)

Sept, 13: Chiller failure( 45’ DT)

- one of the two stirrers failed.

- hardware problem switched to the Backup Chiller System immediately, HVAC investigated the problem later.

- safe to run the chiller with one stirrer for few days, spares were ordered.

- both the stirrers replaced on 09/22 during an MD, one spare kept in case of future failures.

DIRC Crew

10

Operations (5/5)

June, 20: Discovered and unplugged a Xmas tree in sec 1 during ROD. Two new Xmas trees found in sectors 5 (7/26) & 3 (9/12) to be unplugged during shutdown. Xmas tree rate is NOT increasing !

DIRC Crew

year X’ tree

2000 4

2001 2

2002 6

2003 6

2004 3

2005 4

Sept, 27: Front-end power supply failure - Sector 9 FEE stopped communicating with epics - required detector access, unfortunately the hall crew needed to open the door was not available for 24 hours - DIRC taken out of data-taking in this period - problem in power supply (ps) identified and ps replaced

Sept, 28: Niels (with help from Jim Hamilton) fixed problem with global calibration and implemented some useful new features for online monitoring.

11

DIRC Backgrounds

• DIRC background estimated by Jerry’s formulation

• New variables defined for monitoring: Scaler Value/ Expected Scaler Value

• Expected scaler rate is a linear function of IHER , ILER & luminosity

• Very high bkg in June-July associated with ‘low’ luminosity

• Significant improvement in August and September

• Background levels are now similar to what they were at the end of Run 4 (expected rates are conservative)

Jerry V Nicolas A et al

April May

June July

August September

luminosity

Sca

lar

ratio

1

1

1

12

• Water transmission, resistivity and acidity stable

• PMT glass removal rate: 5 /yr << 1000 front glass thickness

• Low bacteria level • For details see :

DIRC Water Quality Jerry V

http://babar-hn.slac.stanford.edu:5090/HyperNews/get/DIRCOper/1717.html

13

Spares status

Front End : OK HV boards: OK FEE Fans : see the next slide We have dedicated web-pages to monitor spares

Summary list of all spares:http://www.slac.stanford.edu/BFROOT/www/Detector/DIRC/Operations/spares.html

List of current boards used in the DIRC:http://www.slac.stanford.edu/BFROOT/www/Detector/DIRC/Operations/boards.html

List of all boards with internal and slac IDs:http://www.slac.stanford.edu/BFROOT/www/Detector/DIRC/Operations/slacid.html

A good situation overall

Kalanand M

Nicolas A

Emmanuele S

14

Shutdown Plans (1/3)

Shutdown schedule: doors opening on Mon 10/10 work could start on Tue 10/11 bridge in Wed 10/19 ( Curtain wall permitting )

bridge out Thu 10/27 doors closed Fri 11/10

Main Planned Activities: To change all the FEE fans in all sectors (see next slide) To plug out the two Xmas trees (in sectors 3 and 5) Test spare HV boards

Two N2 flow-meters to calibrate ( sectors 0 and 10 )

Fri 10/21

DIRC Crew

15

Replacement of fan trays:

Shutdown Plans (2/3)

All fans in our FEE (total 108) to be changed. Details already finalized in the October shutdown planning.

• FEE Fans are reaching their “expected lifetime”.• 2 fan failures since last December.• 3 out of 9 fans per sector cannot be bypassed via epics A failure of any one of them would require opening the door ( ~ 2 shifts ).

DIRC Crew

16

Replacement Schedule: - Fan trays from bottom sectors to be replaced first: 8 sectors

reachable from ground / with ladders

- Expected rate: up to 2 trays / day

- Switch on a crate immediately after its fan replacement to let the fans run as long as we can

- When bridge is installed, 4 fan trays already replaced will

be moved from bottom sectors to top ones

- All fans will run for more than 2 weeks before doors are closed ! ( To remove any chance of infant mortality )

Shutdown Plans (3/3)

DIRC Crew

17

Conclusion

Safety procedure: in place. Fast monitoring: improved. Data Quality: OK. Operations: all problems encountered were fixed. Background studies: in progress.Shutdown plans: finalized. Manpower shortage during most of the year

complicated the ops crew’s task. We expect the situation to improve soon and to be significantly better in 2006. Welcome Emmanuele and Rolf !

Kalanand M

again !