ALFA testbeam résumé

Dennis Petschull

Deutsches Elektronen-SynchrotronHamburg

DESY ATLAS Meeting, Zeuthen

D. Petschull ALFA testbeam résumé 2008-09-08 1 / 10

Motivation Testbeam results Conclusion & outlook

Outline

1 Motivation

2 Testbeam results

3 Conclusion & outlook

D. Petschull ALFA testbeam résumé 2008-09-08 2 / 10

Motivation Testbeam results Conclusion & outlook

Short reminder about ALFA

Figure: Elastic scattering event at IP1

ALFA setup and purposeAbsolute Luminosity For ATLAS

Roman Pots at ∼240m from IP1

Measure elastic scattering at very small angles

D. Petschull ALFA testbeam résumé 2008-09-08 3 / 10

Motivation Testbeam results Conclusion & outlook

Short reminder about ALFA

Figure: Exploded view of an ALFA Roman Pot Unit

Detector layoutMovable ”Roman Pots” approaching beam from top and bottom

Detectors using scintillating fibres on Ti-plates

Scint. light→ MAPMTs→ PMFs→ motherboard

D. Petschull ALFA testbeam résumé 2008-09-08 3 / 10

Motivation Testbeam results Conclusion & outlook

Why a testbeam?

Status before testbeamMechanics of one Roman Pot completely assembled

FE electronics debugging ongoing

DAQ and reconstruction software under development

Why going into testbeam?Test all components under ”real” conditions

Check if estimated resolution is achievable

Gain some experience with electronics and DAQ

D. Petschull ALFA testbeam résumé 2008-09-08 4 / 10

Motivation Testbeam results Conclusion & outlook

Why a testbeam?

Status before testbeamMechanics of one Roman Pot completely assembled

FE electronics debugging ongoing

DAQ and reconstruction software under development

Why going into testbeam?Test all components under ”real” conditions

Check if estimated resolution is achievable

Gain some experience with electronics and DAQ

D. Petschull ALFA testbeam résumé 2008-09-08 4 / 10

Motivation Testbeam results Conclusion & outlook

Testbeam schedule: forseen and real

Forseen scheduleH8 testbeam stand in the SPS experimental halls at CERN

Beamtime: July 15 - July 21 and August 6 - August 26Electronics-, LED- and possibly cosmics-test in bldg. 251 untilAugust 1⇒ move all equipment incl. Roman Pot Unit to H8 area afterwards

3 weeks of data taking

D. Petschull ALFA testbeam résumé 2008-09-08 5 / 10

Motivation Testbeam results Conclusion & outlook

Testbeam schedule: forseen and real

Real scheduleHeavy motherboard problems in bldg. 251; DAQ not running stable

August 12: test-setup dissambled in bld. 251 and moved to H8

Electronics still causing lot of trouble in H8

August 20: motherboard replaced with spare and testmotherboardsAugust 21: feedback from the detector; track patterns in the fibersand the silicon telescope with correlation between both

BUT: not using the final electronics which are going into LHC

August 25: actual motherboard (Lund) debugged and installed;still minor problems with DAQ software

D. Petschull ALFA testbeam résumé 2008-09-08 5 / 10

Motivation Testbeam results Conclusion & outlook

ALFA Electronics

Figure: Exploded view of an ALFA Roman Pot Unit

D. Petschull ALFA testbeam résumé 2008-09-08 6 / 10

Motivation Testbeam results Conclusion & outlook

ALFA Electronics

D. Petschull ALFA testbeam résumé 2008-09-08 6 / 10

Motivation Testbeam results Conclusion & outlook

Overall testbeam summary

(Temporary) problems:Electronics: motherboard and FE electronics not working together

Software: DAQ from silicon telescope and ALFA detector notworking together

Unstable beam conditions

Achievements:Collected altogether one million triggers with different parametersettings

In the end: several successful runs with Lund motherboard

All participants gained a lot of insight into ALFA electronics,mechanics and software

D. Petschull ALFA testbeam résumé 2008-09-08 7 / 10

Motivation Testbeam results Conclusion & outlook

More detailed testbeam results

Activities in bldg. 251LED instead of fibre detector

verify MAPMT and fibre mapping

measure S-curves

all kapton cables and different HV settings

D. Petschull ALFA testbeam résumé 2008-09-08 8 / 10

Motivation Testbeam results Conclusion & outlook

More detailed testbeam results

Activities in H8 area (chronological):Lund motherboard:

I ∼200 ns latency problem with motherboardI all kapton cables; delay scanning from 100 to 300 nsI ∼150.000 triggers counted

2 Orsay test boards:I only 2 kapton cables connected→ 10 PMTsI parameter scans: HV, kapton combinations, gain, DAC and x/yI ∼650.000 triggers counted

Lund motherboard:I all kapton cablesI measure S-curvesI reduced parameter scans: HV, DAC and x/yI ∼370.000 triggers counted

D. Petschull ALFA testbeam résumé 2008-09-08 8 / 10

Motivation Testbeam results Conclusion & outlook

Preliminary plots

Figure: First results from online reconstruction: beam profile on diamondshaped ALFA trigger counter (left); two possible tracks in fibre detector (right)

D. Petschull ALFA testbeam résumé 2008-09-08 9 / 10

Motivation Testbeam results Conclusion & outlook

Conclusion & outlook

ALFA testbeam with fully equipped Roman Pot at CERN inJuly+August 2008

Long struggle with electronics and unstable DAQ software

Finally (last 5 days) successful data-taking with actual electronicssetup

Testbeam data analysis will give details about ALFA project as awhole

D. Petschull ALFA testbeam résumé 2008-09-08 10 / 10