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MEG 2009 Run

This MEG review provides an overview of the 2009 run, highlighting issues investigated and planned implementations for 2010. It also covers the schedule modifications and access improvements for shift coordinators.

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MEG 2009 Run

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  1. MEG 2009 Run Run Coordinator’s View! MEG Review February 2010

  2. DC – HV stability Review 2009 Successfully finished first MEG Physics Run (Sept. – Dec. 2008) APD - electronics • However – Major Issues to be Investigated/Rectified: • DC: high-voltage stability (He-diffusion problem) • Calorimeter: LXe light-yield LY (reduced absolute LY  ) • Calorimeter: PMT gain-drift (reduced gain with >Qbeam) • TC: fully functioning fibre detector (new APD readout) LXe - calibration MEG Review February 2010

  3. Situation Spring 2009 Post Review February 2009: Back to “Square One” – TOTAL Detector DISMANTLED for Maintenance/Repair /Improvement Shutdown 2008 / 2009 + Kottmann Expt. Front-part E5 Scheduled until mid-July! Calorimeter – > cooling-power (<LN2) Modify purification System – new Getter (< contamination) & Liquid Pump (LY) Dismantling of all DCs New anode-prints + wires + extensive tests “aquarium” & “He-cabin” +… (HV stability > ) New APD front-end electronics + control interface (reduced noise + faster -> trig) MEG Review February 2010

  4. Further planned Implementations 2009 • (I) Upgrading from DRS2 to DRS4 • differential i/p • internal clock & synchronization • on-board timing calibration • 3.2 GSPS possible XEC-1.6GHz • DC  0.5 GHz but >0.7GHz • (2) Change of degrader thickness at BTS focus • 300m Mylar to 200m Mylar • to match 6 % air contamination • content in COBRA (previously variable) • & centre stopping distribution in target One main aspect which ran in parallel during the first half of the year was the ANALYSIS of 2008 DATA!!!! MEG Review February 2010

  5. Schedule 2009 • Kottmann et al. beam time until mid-July • DRS4 installation end-July • Parasitic Run (detect. set-up, beam tests e.g. Deg., e+) • beg.-Aug.- mid-Sept. • e+-test +CEX calibration run mid-Sept. – beg-Oct. • Remainder of year • - Physics data-taking • expectation ~ 2½ months MEG Review February 2010

  6. Schedule Modification • “Exciting Results” from • Lamb-shift Expt. • Causeda shift of • MEG start up by • 3 weeks!!! • CONSEQUENCE: • In order to enough time • To calibrate detector • & • obtain usable statistics •  • Test beam time reduced • to absolute minimum • No degrader optimization • No positron beam tests MEG Review February 2010

  7. Parasitic Run 12 Hr Shifts: 1 DAY SHIFT (Beam Group) 10:00 – 22:00 1 NIGHT SHIFT max. 22:00 – 10:00 1 Shift Leader Nights Manned by Detector Experts Basic Run Layout Parasitic Run Beam optimization in parallel with Debug, Tune & Calibrate Full Run Part I CEX Run + Trigger Setup + calibrations Detector monitoring Full Run Full Run Part II Pre-physics data check Physics Data (MEG + mixed triggers) 8 Hr Shifts: 1 DAY SHIFT 07:00 – 15:30 1 EVENING SHIFT 15:00 – 23:30 1 NIGHT SHIFT 23:00 – 07:30 1 Shift Leader + 1 Crew Member Organization Similar structure to 2008 Run Coordinator 2 Shift Coordinators  6 weeks tot. 13 Shift Coordinators  1 weeks/person Total of 55 persons for 592 shifts (Full Run Only) • to allow for flexibility + continuity: • Staggered & Overlapping shift system • Daily Run Meetings (on-site) • Weekly Video Run Meeting (Collaboration-wide) • later, weekly Video Physics Analysis Group Meeting • Web-based Schedule + Shift list + “On-call” List MEG Review February 2010

  8. Access to FE-crates Access to DC-HV Access to all MSCB sub-masters Practical Additions - Monitoring • MIDAS – DAQ control page: • web-access to all MSCB sub-masters & nodes • web-access to FE crates status, temp, fans, ON/OFF • web-access to DC HV-control • web-access to Online Analyzer • improved Offline analysis jobs for shift crew • All towards the long-term GOAL of Remote Shifts…. MEG Review February 2010

  9. TCs: • APD electronics induces too • higher noise level in DCs •  Switched OFF • APD DAQ control problems • still Laser temp. control problems Detector Synopsis TCs • Beam: • BTS He cold leak around JT- • valve solved temporarily for • run • Degrader change from • 200m to 300m during Run • stopping distribution problem • Calo: • Liquid & Gaseous • purification success • optimal LY achieved • further study PM gain • stability DCs Beam • DCs: • HV instability problems • solved, fully efficient • Resolutions? Calo. MEG Review February 2010

  10. lcmeg05 lcmeg04 lcmeg03 lcmeg02 lcmeg01 Online Cluster Megonxx Trigger + Splitters Trigger + DAQ Synopsis • Trigger: • Full Complement of 29 Triggers with pre-scaling used • E-resolution improved 20% (7.5%FWHM @ 55MeV) •  > thresh. • Z-resolution Zrec- ZTC(Qratio) improved ~23% (5.5cm) • Direction matching  e with fibresstill missing !!! • APD(OFF)  XEC(PMT-index) + TC-bar(index,z) • where z from bar charge-ratio • Implementation of -trigger during beam=“ON” <TCALIB • Trigger#0 TC eff. loss ~25% due broken LVDS transmitter • for first-part of the run • FE-electronics: mostly NEW! • DRS4 teething problems: synchronization + jitter DRS4 + part DRS3 • DAQ: • LT~84%, DAQ inter-run time reduced by > 4x • DAQ online monitoring & control - many additions • Online (backend) 2 TB storage • Offline (lcmeg) 64 CPUs + now 150 TB disk • “Lazylogger” autocopy Online  Offline • factor 2 compression offline Offline Cluster lcmeg MEG Review February 2010

  11. - target inclination angle 2009 Run Conditions • Target Angle: - similar slant angle  as 2008 • Conventional = (20.6 ± 0.2)° • Photogrammetric • (outside COBRA) = (20.4 ± 0.2)° • Photogrammetric • (inside COBRA) = (20.3 ± 0.3)° 2008 <> = (20.5 0.3)º Target Inclination 2009  = (20.0 ± 0.3)° provisional • Degrader: two settings used during Run • 200m & 300m Mylar & 94%He/6%Air • Beam Intensity: - on average 10% > IPROT compared 2008  2 main modes tuned • “Normal” – same slits as 2008 & “Normal*8” – slits diff., same absolute rate as 2008 Stopping rate for physics Run (300m degrader) at 2.2 mA ~ 2.9·107+s-1 MEG Review February 2010

  12. t=205 m l=585 m Horizontal Profile 0.8 mm high Degrader Question 200m GEM Monte-Carlo 2008 Shows stopping US of target centre by > 50m CH2 for a target thickness of 205 m 4.3% Air Equivalent to 140 m CH2 Along l or ~ 100 Mylar 300m Degrader GEM 2008 4.3% Air Remember 100m of degrader Equivalent to ~ 24% of target thickness ONLY!!! Therefore should just shift peak of stopping distribution inside of target Conclusion: Remove 100m of Mylar i.e. go to 200m thickness to centre stopping distribution 2009 Physics Run started with 200m Degrader since optimization skipped due to time Measured 200m Measured Vertical Profile 0.5 mm Aare Vertex Distribution Using Michels MEG Review February 2010

  13. GEM 2009 6% Air 200 300 strong asymmetry in TC US/DS hit-maps seen??? GEM vs Data 100 300 m Degrader Example MEG-trigger Data 2009 Run# 59040 200 m Degrader Example MEG-trigger Data 2009 Run# 53000 • GEM 2009 – • confirms central shift • BUT!!! • Data features not all • reproduced e.g. • Asymmetries • stopping with no target Timing problem TC-US Enhances Asymmetry For MEG-data TIC-asymmetry DS/US ~ 4.3 TIC-asymmetry DS/US ~ 1.3 GEM/Data: *** US-TC enhancement MEG Review February 2010

  14. Degrader Conclusions Motivation: Originally 2008 degrader of 300 microns changed to 200 microns in 2009 to optimize stop-distribution to centre of the target for now fixed 6% Air-admixture amongst other information, this was supported by GEM Monte-Carlo However – strong asymmetry in TC US/DS hit-maps seen??? Changed back to 2008 situation during Run Run Condition 200 Physics Data: 29/10 – 23/11 DAQ-time: 14.0D 300 Physics Data. 26/11 – 23/12 DAQ-time: 21.2D • Relative Muon Stopping Statistics 2009/2008: • DAQ-time 2009/2008 = 0.732 Dominant factor! • Relative time-weighted stopping-rates 2009/2008 = 0.866 (all 300 data = 0.94) •  (2009: stop200~56%, stop300~82%) – relative values from Michel data • Relative Stopping Statistics: SS2009/SS2008 = 0.634 Dominated by run time! • However true relative statistics 2009 much better since spectrometer tracking efficiency • & trigger efficiency much better than 2008! factor ~3.5 x 0.634 = ~ Factor 2.2  MEG Review February 2010

  15. Degrader Conclusions cont. Conclusion: MC does not support “strong leakage” from DS-face for 200m case detailed check & MC-study underway Necessary to perform optimization beam test using different degrader thicknesses Will be performed spring 2010 • measuring stopping-rate by counting Michel e+ using reconstructed tracks • originating from the target volume vs. several degrader thicknesses • measure “No-target” stop distribution for above degrader thicknesses to compare • with & tune/optimize MC MEG Review February 2010

  16. Fore-valve OPEN CLOSED isolation vacuum Further Aspects of 2009 Run • BTS: He transfer-line coupling + Joule-Thompson Fore-valve region, cold-leak • (meant BTS had to be warmed-up & JT-tower opened + additional pump-stand introduced • that could work in B-field environment) Transfer-line coupling FV < 7.5% He leak Detection Open: 3·10-7mbls-1 Closed: >7·10-6mbls-1 BTS JT-Tower • Problem solved for Run: • New In-coupling transfer line • New additional pump-stand • for isolation vacuum FV-OPEN MEG Review February 2010

  17. FE-Electronics • FE-Electronics: • (teething problems with DRS4 implementation took much longer than anticipated • involving both software & hardware modifications • also the new architecture 4-chips/2-chips - • necessitated the total re-doing of the zero-suppression algorithm; physical displacement of • cross-associated anode & cathode channels to different modules) • DRS4 clock synchronization • DRS4 large dispersion in inter –channel, -chip, -board, -crate time-jitter • DRS4 spike & ripple suppression • DC zero-suppression algorithm • Noise problems: • (Fourier power spectrum analysis –showed various source frequencies- high frequency • range associated with APD electronics resulting in TC fibre system not being used) • Environmental noise – seen by DC & TC systems • New APD Fe-electronics producer/propagator of high noise-levels on DC • readout Details Stefan talk Details Flavio talk MEG Review February 2010

  18. LXe Aspects Calorimeter: 2008 Light-yield < expected both for s & s (Q/A)/(Q/A)~ 1.25 expect LP ~ 1.92!!! Contamination? new purifier installed Liquid & Gaseous & No purification scenarios studied • Light-yield proved to be stable @ 1% level during 2009 Run • Achieved absolute LY gammas & alphas as expected • long-term PMT gain-drift still not understood ~ 6% drop over run • monitored extensively by many tools – can be compensated for • with HV-adjustment if necessary – problem still being studied • gain-variation with beam-loading well understood –new ideas GainChronology 2009 Run SKB (Q/A)/(Q/A) ~ 1.92 !!! SKB = cathode blue sensitivity vs. serial no – shows possible link of gain to too much alkali? Rel gain-shift Serial No MEG Review February 2010

  19. Run 2009 93 TB data Beam Time/Data In view of the extremely tight schedule for starting from “scratch” with the set up in E5, also with Lamb-shift extension + numerous detector/electronics etc. problems to be solved … Managed (in real days) 55% of 2008 physics data-taking & approximately same number of triggers • MEGDATA • 200m (Runs# 51824-57184) • 5313 Runs a 2k events • 10.64 M Triggers • Time 14:00.31.17 300m (Runs# 57582-64482) • 5775 Runs a 2k events • 11.63 M Triggers • Time 21.05.25.07 Parasitic Run:1st September- 15th September ~ 2 weeks Beam Tests/Tuning (~1 week) Full Run Part 1:16th Sept. – 30th October ~6 weeks CEX 12th October– 24th October (12 days) Full Run Part 2:25th October – 22nd December ~8½ weeks Physics Data 200m Degrader ~17.5 Days Physics Data 300m Degrader ~25.5 Days • Normal Physics Data-taking: • MEG 12-mixed trigger • 6 Hz Trigger Rate, LT~84% 300m Degrader • 10 Hz, 75% LT 200m Degrader • Daily LED-calibration beam “on-off” • 3/week Full-calibration LED beam “on” +LED beam “off” • + C-W (Li) + C-W (B) + s Total of 93 TB Data Taken 2009 MEG Review February 2010

  20. Conclusions 2009 • Of the original expected ~11½ weeks of physics data-taking (MEG Schedule) minus • the 3 weeks extension granted to Lamb-shift expt. We managed to take ~ 8 weeks of • MEG data! • The major problem encounter during the 2008 Run (DC HV-instability) was solved and the • chambers ran with “full efficiency” • The LY of the calorimeter also “plateaued” at its expected value allowing /-discrimination • with beam “on” enabling continuous monitoring during MEG data-taking – LY stable over • extended period of time to ~ 1% level WITHOUT further purification!!! • The LXe PMT long-term gain-drift is not understood yet though enough tools available to • monitor & sufficient HV-reserve so not problematic. Beam correlated gain variations well • studied – strategy for UCN beam structure being further studied. • Reduction of the timing-jitter from DRS4 channels on different boards is being studied • together with the possibility of running at higher frequency • TC fibre-detectors which could not be used in 2009 due to large induced noise on the DC • electronics are being modified & expected to be fully functional for 2010 MEG Review February 2010

  21. Conclusions 2009 cont. • Fine-tuning of the degrader with beam and a check of the range-straggling in COBRA • without a target, for MC comparison/tuning, will be undertaken • The postponed test of a monochromatic positron beam which would allow the energy • dependent study of our positron spectrometer resolutions as well as the relative • acceptances, will be scheduled • Many of the outstanding questions concerning detector performance: DC cathode foil • aging,TC fibre detector noise suppression, DC-survey position, magnetic field symmetry, • chamber resolutions etc. are now being addressed or to be answered soon! • – MORE TIME NEEDED! • This overview was meant as an introduction to the following “Expert” talks MEG Review February 2010

  22. Finally A substantial portion of the year was ALSO utilized to analyze our 2008 Physics Data In parallel to solving the previous outstanding problems. The Preprint: Is now ready for submission for publication! MEG Review February 2010

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