FMS Update: Spin PWG

Stephen Trentalange April 16 2015

Summary of FMS Operations • FMS is performing well and is fairly stable.

– No sign this year of runaway trigger – Solved problem with Lecroy Voltage instabilities

• Monitoring programs by Chris Dilks • Repair and Replacement of unstable cards/controllers: Chris Dilks

– Minor HV problems with small cells (loss of 8 cells) • Replacement daughter boards being repaired/fabricated by PSU • Receive replacements this week. Need spares.

– Replacement of DSMs(1) and QT boards(4) during run • Bit checking and monitoring of problems by Akio Ogawa

– Damage to lead glass • Trigger rate monitor by Chris Dilks • Evaluation of damage by Steve Heppelmann/S.T.

• FPS is installed and running: Data being examined by Akio Ogawa • Correlations with Roman Pot Triggers being examined: Chris Dilks • We have achieved our goals for p+p transverse and (most likely) p+p

longitudinal (limited by syst error in rel. luminosity) • Propose new voltage iteration before end of longitudinal running to

compensate for gain loss: prepare for p+Au run

BUR Runs 15-17

FMS 200 GeV Transverse/Longitudinal Run

Have achieved transverse goals in luminosity and FOM, probably even after QA cuts; Longitudinal is ~50% of central rapidity goal. Comparable to previous years.

FMS Run QA: Christopher Dilks

Acceptance/Relative Luminosity

http://www.star.bnl.gov/protected/spin/dilks/scalers2015t/

Pions/Gammas/Jets

https://drupal.star.bnl.gov/STAR/blog/heppel/asymmetry-update

π/γ/jet Asymmetries: (~10% of data) http://www.star.bnl.gov/protected/spin/dilks/15tran/asym_plots/asym_web.html

Transverse Momentum [GeV/c]

Pion Energy [GeV]

A TT

A N

AΣ

A N

AN

AΝ

Indications from Preliminary Analysis

• No major problems with analysis chain • Possible indication of interesting behavior at

low pT-> may wish to lower threshold/prescale for SmBS1 for p+Au running? (Steve Heppelmann)

FPS Status Gain adjusted to MIP=100ch (50ch for layer3)

Pedestal cut adjusted to reduce data volume >5*RMS from HV off pedestal => fixed to ch>9

Q1L1

Q1L2

Q1L3

Q2

Q3

Q4

1 Bad channel

ADC Ch (1/4pC)

Q1L1S4

FPS Monitor: http://online.star.bnl.gov/fps/

FPS is running well

ADC ch

http://online.star.bnl.gov/fps/

Radiation Damage to FPS SiPM Current [uA] @ operating voltage (beam off)

IV scan run# (~day) Feb6 April16

layer3

Layer1 & 2 Red=near beam Green= middle Blue=far from beam

Radiation damage to SiPM increased leakage currents from ~0.1uA to ~40uA some hit 52uA = FEEBd limit to measure current Gerard expect FEE HV problem at >100uA (can be modified)

2 sets of 10 TLDs were installed around FPS/FMS Each stayed 4 weeks (under analysis) 3rd set will be installed for pAu

FPS Pedestal Pedestal @ PHYSICS voltage

ADC Ch (1/4pC)

Pedestal Monitors: https://www.star.bnl.gov/protected/spin/akio/fpsPedMon/

Radiation damage increased pedestal RMS from ~1 to ~5ch

Q1L1S4

Pedestal RMS @ PHYSICS voltage & beam off

FPS pedestal run# (~0.5day) April12 Feb9

https://www.star.bnl.gov/protected/spin/akio/fpsPedMon/

FMS-FPS correlation FPS layer3 slat# with >1/2 MIP hit

ABS(FMS point Y position[cm])

Q1L3 Q2L3

Q3L3 Q4L3

• StFmsPointMaker to find FMS point (PSU codes in STAR framework)

• StFpsRawHitMaker in CVS

• Normalized with FMS Y position

distribution (otherwise spikes due to single cell cluster dominate the plot)

• Weaker but similar correlation seen in Layer1 & 2

• Found 3cm misalignment for Q1/Q2 X position vs FPS layer1:

FMS known ~3cm shift was not in DB yet More details at https://www.star.bnl.gov/protected/spin/akio/fms2015/ Adding FPS tag to FmsPoint coming soon

https://www.star.bnl.gov/protected/spin/akio/fms2015/https://www.star.bnl.gov/protected/spin/akio/fms2015/

FMS from Survey

South side shifted X=+32 mm from center line

Damage to Lead Glass

7.4 pb-1

24.6 pb-1

47 pb-1

Damage to Lead Glass No observed effect on pion or eta mass position or pion mass resolution Delivered Luminosity: (40 pb-1 ) (error bars smaller than points)

Mass Peak Position: Day 92/Day 80

Pion Mass Resolution: Day 92/Day 80

Slope of pT distribution vs time: Slope INCREASES slightly!

Day

Slop

e of

pT

Dist

ribut

ion

Pseudorapidity

Damage to Lead Glass: Pion Yields/Luminosity by Steve Heppelmann

Pion Yield/Unit Luminosity decrease ~7%/day: Decreases by factor of 0.565 for 17 /pb or -2.5%/pb-1 . What gain loss does this correspond to?

Scaling of Pion Spectra

0.9*pT

Trigger Threshold

Compare integral of pion yields over threshold for original and scaled pT spectra- Roughly factor of 5 difference: Decrease of trigger rate by 50% means decrease of gain by 10%. For the small cell tubes (PMT gain ~Vα with alpha = 4 or 8). To compensate for a gain loss of 10-20% implies a voltage increase of ~2-5%.

Voltage Compensation for Damage to Lead Glass over 200 GeV Running

• -0.025 /pb -> factor of 0.975 /pb • Assume 200 /pb delivered during Run15

– 90 /pb p+p – 300 /nb p+Au x 200 = 150 /pb sampled

• (1+ 0.025/(pT slope*PMT gain exponent))**L – (1+0.025/(5*4))**200 = 1.28 – (1+0.025/(5*8))**200= 1.13

• Increase voltage on small cells 13-28%

Conclusions • FMS is performing well and is fairly stable.

– FPS Installed • Stable running • Monitoring radiation damage • Correlation with FMS hits observed

– RP data read out with FMS • Initial analysis shows FMS pion asymmetries correlated with RP

triggers • Must evaluate multiple events per crossing to say more

• We have achieved our goals for p+p transverse and (most likely) p+p longitudinal.

• Propose new voltage iteration before end of longitudinal running to compensate for gain loss and to prepare for p+Au run.

• New iteration should adjust gain of innermost cells by +10-20% -> voltage change of +2-5%.

Backup Slides

~15% of small cells radiation hardened lead glass: needs no voltage adjustment

Day

92

/ D

ay 8

0

LED Peak Ratios

FMS Update: Spin PWGSummary of FMS OperationsBUR Runs 15-17FMS 200 GeV Transverse/Longitudinal RunFMS Run QA: Christopher DilksAcceptance/Relative Luminosityp/g/jet Asymmetries: (~10% of data)Indications from Preliminary AnalysisSlide Number 9Radiation Damage to FPS SiPMSlide Number 11FMS-FPS correlationFMS from SurveyDamage to Lead GlassDamage to Lead GlassDamage to Lead Glass: �Pion Yields/Luminosity by Steve HeppelmannScaling of Pion SpectraVoltage Compensation for Damage to Lead Glass over 200 GeV RunningConclusionsBackup Slides