Detector Stability Analysis Using MoRI Data David Barnhill UCLA

Motivation Monitor detector performance of key quantities: –Anode and Dynode Baselines –VEM Area and Area/Peak –Dynode Anode ratio Detect any peculiar behavior as a function of temperature and/or time Check Quality Assurance specifications suggested in November meeting

Method We analyzed 188 preproduction tanks from January to February this year We used LS Calibration Data (MoRI) We analyzed RMS over this period for Anode and Dynode baselines and RMS/Mean for Dynode/Anode, VEM Area, and Area/Peak for each tank We also looked at behavior over time and as a function of temperature * In the next slides: –Then = September – October 2003 –Now = January – February 2004

Typical Baselines vs. Time Then Now

Anode Baseline RMS Then Now 45 over 2 channel RMS 15 are due to pedestal readjustments 30 out of spec – 5.3% 3 out of spec – 2.2%

Dynode Baseline RMS Then Now 32 over 2 channel RMS 8 are due to pedestal readjustments 24 out of spec – 4.3% 1 out of spec – 0.7%

Baseline RMS vs. Station ID Anode Dynode

Baseline Problems All 6 channels => FE problems? (~10 tanks)

Temperature Coefficients - Baselines Anode Then Now

Temperature Coefficients - Baselines Dynode Now Then

Typical LS VEM vs. Time and Temperature Then

Typical LS VEM vs. Time and Temperature Now

VEM Area vs. Station ID

LS VEM Area Then Now 29 over 5% 11 due to recalib. 18 out of spec – 3.2% 6 out of spec – 4.4%

Tank 205 (Mage) VEM Area PMT 1 seems to be decaying Then Now

Temperature – LS VEM Area LS VEM Area Then Now

Temperature Problem As documented in Bugzilla: – There is a known problem with temperature causing jumps in certain quantities –Tanks 116, 147 and possible 158 and 167 Problem is known, but cause and solution are unknown

Tank 147 VEM Area ThenNow

Tank 116 VEM Area ThenNow

New Problems

Typical LS VEM Area/Peak vs. Time ThenNow

Area/Peak vs. Station ID

LS VEM Area/Peak Then Now All 3 PMTs in each tank affected 35 over 5% -> 6.2% 2 out of spec – 1.5%

Temperature - LS VEM Area/Peak Then Now

Typical Dynode/Anode Ratio ThenNow

Dynode/Anode vs. Station ID

Dynode/Anode Then Now 8 out of spec -> 1.4% 7 out of spec -> 5.1%

Dynode/Anode Problems

Temperature – Dynode Anode Ratio Then Now

Tank 128 (Vatly) Dynode/Anode No entries in bugzilla ThenNow

Dynode/Anode Spiky Behavior - Gone ThenNow

Quality Assurance Specifications NOW THEN

Stability Conclusions Pedestals: –All due to ~10 tanks with varying pedestals on all 6 channels Area/Peak: –All 3 PMTs in a tank affected when one goes bad ~13 tanks –Statistics looks bad, but roughly divide 6.2% by 3 = ~2% problem Dynode Anode ratio is more consistent and stable, 3 PMTs with bad D/A problem only VEM Area –Temperature correlation issues ~7 PMTs –Other problems ~3 PMTs Tanks with PMTs failing multiple specs: –102, 193, 214, 262

PE at 1 st Dynode

PE at 1 st Dynode vs. Gain