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MEG 2008 Run Run Coordinator’s view

. E e /E Max. MEG 2008 Run Run Coordinator’s view. Situation - Review Feb. 2008. Back to “Square One” - TOTAL Detector DISMANTLED post 2007 Engineering Run - for Maintenance/Repair /Improvement. TCs: Fibre light-leak + new N 2 Bags + APD amplifier/electronics. DCs. TCs. TCs.

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MEG 2008 Run Run Coordinator’s view

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  1. Ee/EMax MEG2008 RunRun Coordinator’sview MEG Review February 2009

  2. Situation - Review Feb. 2008 Back to “Square One” - TOTAL Detector DISMANTLED post 2007 Engineering Run - for Maintenance/Repair /Improvement TCs: Fibre light-leak + new N2 Bags + APD amplifier/electronics DCs TCs TCs DCs: Support Structure + new Target Angle + HV Investigation EC C-W Calo: new HV Feed-thro’s + LN2 Cooling-pipe mod. (heat-load) + lnvest. LXe Light-Yield mod. Purification system DS-EC + IS BTS Calo. MEG Review February 2009

  3. 2008 Beam Time & Constraints • 2008 Run Goals: • final beam operational conditions to be tuned/optimized {(-, - & p-beams C-W)} • Full set of detector calibrations + optimization/exploitation of various techniques • optimized detector/trigger settings • asfuller set of information as possible, necessary for Data-analysis • + “Long-term” Goal of understanding our Detector End-of-Shutdown Max. Expectation MEG-Physics Data ~ 16 weeks MEG Review February 2009

  4. 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 + RD) 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 Planning & Organization Run Coordinator 2 Shift Coordinators  7 weeks tot. 13 Shift Coordinators  2 weeks/person Total of 62 persons for 959 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 2009

  5. 5 Sheets Organization In Practice • Detailed Information Access • “How to” information database for shift crews on MEGWiki • fully searchable & cross-referenced Electronic • Logbooks for all sub-detectors & Run shift-crews Shift List EXAMPLES • comprehensive electronic Hardware/Software • check-list for shift crews • easy web-based experiment/instrument • control for shift-crews • (e.g. Beam Line – magnets, separator) • push-button changing of rate with auto • magnet/slits hysteresis cycling Schedule MEG Review February 2009

  6. TCs DCs Detector Synopsis • TCs: • Fibres working, problem • DAQ control of DS fibres • Laser temp. control problems • DCs: • HV instability problems with • air-doping still persist!!! • Calo: • HV feedthroughs replaced • Liquid & Gaseous purification • success LY-behaviour needs • further study + PM gain stability • NaI: • New APD preamps • automated mover • temp. contolled APDs • E/E ~5-6% () • C-W: • proved “Essential Tool” • Li (17.6, 14.6 MeV) • + B (4.4, 11.7, 16.1 MeV) • lines – Energy + Timing Calo. C-W NaI MEG Review February 2009

  7. lcmeg05 lcmeg04 lcmeg03 lcmeg02 lcmeg01 Online Cluster Megonxx Trigger + Splitters Trigger + DAQ • Multi-trigger implementation: • Final Complement of 29 Triggers implemented • multiple & pre-scaled (MEG=11, RMD=5) • Single & Coincidence detector triggers crucial • for monitoring/Calibration • e.g. 7Li, 11B C-W, , CR, LED – RMD, 0,0-Dalitz • CEX software collimators LXe responce • Direction matching  e (planned TC fibres) • too slow  still XEC PMT-index + TC-bar(index,z) • where z from bar charge-ratio • Trig. Monitoring via (cyclic-buffers) DRS v2 + part v3 DRS3 – partly implemented (clock signals, temp eff. Etc.) • Limits: • DAQ/DRS readout limited by VME (83MB/s) • ~ 30 events/s full waveforms (threading) • Online (backend) 2TB storage • Offline (lcmeg) 64 CPUs + 104TB disk • “Lazylogger” autocopy Online Offline • factor 2 compression offline Offline Cluster lcmeg MEG Review February 2009

  8. m radiative decay LED Laser Lower beam intensity < 107 Is necessary to reduce pile-ups Better st, makes it possible to take data with higher beam intensity A few days ~ 1 week to get enough statistics g e m (rough) relative timing calib. < 2~3 nsec n n PMT Gain Higher V with light att. Can be repeated frequently p0 gg p- + p  p0 + n p0  gg (55MeV, 83MeV) p- + p  g + n (129MeV) 10 days to scan all volume precisely (faster scan possible with less points) LH2 target Laser alpha MEG Detector Standard Calibrations PMT QE & Att. L Cold GXe LXe e+ g e- Nickel g Generator Proton Acc Li(p,)Be LiF target at COBRA center 17.6MeV g ~daily calib. Can be used also for initial setup 9 MeV Nickelγ-line on off quelle K Bi NaI Illuminate Xe from the back Source (Cf) transferred by comp air  on/off Tl Li(p, 1) at 14.6 MeV F Polyethylene 20 cm 3 cm 0.25 cm Nickel plate Li(p, 0) at 17.6 MeV Arsenal of Standard Calibration Tools NOT YET STANDARD NOT YET STANDARD MEG Review February 2009

  9. 4.4 and 11.6 MeV Compton Edges Energy deposit in XEC “Energy” deposit in TC >11.7 MeV 4.4 MeV >16.1 MeV LY Am/Be ≡ Li New & Improved Calibration Techniques Multiple calibration techniques proved Essential for deconvoluting complex effects • New Lithium TetraborateTarget (Li2B4O7) for C-W: - advantage both Li- & B-lines • simultaneously available without large X-section of F (~ 6-7 MeV), from LiF 11.7 & 4.4 MeV s Coincident in time (94%) & no angular correlation Li used for E-calibration, B can be used for Δtabs(LXe-TC) or Δt(TC-TC(inter-bar)) (2) New timing calibration technique during CEX: - use Dalitz decay for intercalibrating LXe & TC detectors by tracking e+ in DCs(0→ e+e- ) used successfully for measuring absolute Δt(LXe-TC) of reference TC-bar, can then intercalibrate bar using Boron e.g. (3) Am/Be – neutron source as a source of 4.44 MeV Gammas from 2+ state of 12C* via9Be(α,n)12C MEG Review February 2009

  10. Calibration Techniques cont. (4) Use of tuned monochromatic positron beam being investigated as a means of e.g. studying our positron spectrometer tracking efficiency vs. emission angle or momentum, with high statistics, in a momentum range equivalent to real MEG- conditions!!! Mechanism:positron-Nucleus elastic scattering from light nuclei at around Pe ~ 50 MeV/c “Coherent” nuclear recoil, spin-effects, magnetic terms all ~ negligable nuclear form-factor introduces a small effect X-sections “well known” basically “Mott-scattering” • Reality: • MEG beam can be tuned to give ~ 50 MeV/c e+ with a max. rate of • ~ 8· 108 e+/s at 2mA proton current with ΔP/P ~ 7% FWHM • obviously would reduce ΔP/P to achieve “monochromaticity” though at the cost • of rate. • Wien-filter does not work at this momentum to sufficiently separate e+ from + • but a 2mm CH2-degrader at the collimator system in front of BTS DOES! Carbon target ρ ~ 2.1 g/cm3 t < 1cm thick, and 107 e+/s Integrated X-section: 30° < Δθ < 120° & Δφ =  2.5 mbarn  ~ 1300 events/s MEG Review February 2009

  11. - target inclination angle 2008 Run Conditions • New Target Angle: - modification DC Support Structure • optimal @ ~ 21° to match beam stopping distribution etc. • Prior 2008 limited by DC Support structure to max. 13° • Conventional = (20.6 ± 0.2)° • Photogrammetric • (outside COBRA) = (20.4 ± 0.2)° • Photogrammetric • (inside COBRA) = (20.3 ± 0.3)° Target Inclination 2008  = (20.5 ± 0.3)° • Beam Intensities: - apart from “Normal” beam intensity 2 further tunes were • optimized based on standard degrader 300m Mylar – “Ultra-low” & “High” Measured values at 7% air contamination 1% Air ~ 10m Mylar degrader - Not compensated for in 2008!!! MEG Review February 2009

  12. US-EC DS-EC 63 70 61 COBRA 60 62 Run Conditions cont. • COBRA He-Concentration: - for DC HV-stability reasons air-doping of COBRA • Environment was necessary Physics Run Classification: MEG Data ONLY(before/after DC COBRA test) 96% He 92% 95% He 93% P61,P70, P63 O2-sensor P61,P70, P63 Part1: 11/9 (0100) – 20/10 (0100) 35 days Part 2 Part 1 Part2: 27/10 (1149) – 06/11 (2359) – 23/12 11 + 32.5 days P61 blue P70 green P63 red P60 light blue 1% Air ~ 10m Mylar degrader Not compensated for!!! Mean Air-doping (Physics Run Part1 + 2) = 6% MEG Review February 2009

  13. 2008 Beam Time Influences 3 Major factors influenced the maximizing of the available beam time for Physics Data-taking – such that substantial extra investigation time was necessary  (1) Calorimeter:2007 Light-yield << expected both for s & s (Q/A)/(Q/A)~ 1.25 expect LP~ 1.92!!! Contamination? new purifier installed 2008 Significant time was invested with monitoring/understanding of LY vs. purification time Using C-W Li, CR, s & LEDs Liquid & Gaseous & No purification scenarios studied • Calorimeter – Light-yield + PMT gain drift • Electronics - Noise + Baseline stability • Drift Chambers - HV stability Liq.P→ Induced Noise on electronics Gas.P → minimal Noise • Questions to answer: • can one survive without Liq.P for 3 weeks between inter-accelerator shutdowns • and only rely on GasP? • What happens to LY without any purifications? Initial Purification May 2008 L-Y s - 0.7%/5 days also CR same response! s Liq.P No.P Gas.P MEG Review February 2009

  14. PM Gain CEX  - Off Norm Beam 1/2 CEX 2007 Level Beam Time Influences Calo.- cont. • Variations in no Photo-electrons seen…LY changing + ? • PMT- Gain variation seen vs. Beam rate drastic during CEX • changes of several % possible!! Stable at low rate • PMT Gain well monitored using LEDs …Reason for instability? • in principle effect already compensated for “zener diodes”!!! • could this be aging? • Thus frequent LED calibrations used as gain normalization for • light/energy measurements • time constants for rate-changes measured (beam-blocker) • therefore in principle all ingredients available for corrections LY nearly reached optimal value LY is constant LY > How does this affect our energy scale Extrapolated for low-energy low-rate? MEG Review February 2009

  15. B-B “opened” ~30 mins. CEX B-B “closed” C-W Effect on Energy Scale Rate-dependent effect For our Photon Energy-scale we extrapolate from “Low-energy” “Low-rate” C-W data to “High-energy” “High-rate” CEX pion data What is the rate dependency at CEX-rates? Not enough LED data taken during intial CEX  Hence new “mini-CEX” run at end of December ~ 4% discrepancy from Extrapolation to CEX energies before correction from “Mini-CEX” After? better but not perfect! More work needed Before Correction MEG Review February 2009

  16. Beam Time Influences – cont. (2) Electronics: baseline instability as well higher noise content on DRS i/ps 2 reasons found – (i) i/p stages (diodes + resistors)of splitter damaged by sparking from defective Calorimeter feed-thro’s.  all boards modified with new higher rated diodes & resistors changed (ii) burst-noise suppressed with external shielding of flat-band calorimeter cables between splitter & DRS  external shielding added to all calo-cables between splitter & DRS (3) Drift Chambers: HV-stability of chambers persists, seems to be a time dependencybefore onset & seems worsened by CEX pion beam then worsens with time. Gives a complicated time-dependent e+ detector efficiency  Air doping + overpressure + gas-mixture investigated during dedicated combined electronics/Calo./DC maintenance week 100% Anode Hit-map. He-ConC. ΔP(DC-COBRA). 0% MEG Review February 2009

  17. MEG 2008 Run DATA Taken TBytes  139 TB Beam Time/Data In view of the complex & overlapping problems that were studied & monitored during the “Parasitic” & Part 1 Phase of the “Full Run” the following schedule evolved necessitating a mini-CEX at the end of the period to evaluate the rate dependency during the full CEX, so that the Calorimeter Energy-scale could be fully determined: Parasitic Run:19th May- 3rd July ~ 7 weeks Beam Tests/Tuning (4.5 weeks) Full Run Part 1:11th July – 31st August ~7 weeks CEX 21st July – 31st August (6 weeks) Full Run Part 2:1st September – 23rd December ~16 weeks Pre-Physics Data (~ 3 weeks) Physics Data Part1 35 Days MEG Maintenance/Repair ~ 7 Days Physics Data Part 2 43.5 Days Mini-CEX ~ 7 Days • DATA • MEG (Runs# 23987- 40997) • 10859 Runs a 2k events • 22.4 M Triggers • Time 49:18:50:49 RMD (Runs# 23017 – 39963) • 1059 Runs a 3k events • 2.99 M Triggers • Time 7:05:33:39 • Normal Physics Data-taking: • MEG 11-mixed trigger 6.5Hz Trigger Rate, LT~ 80-83% • Daily LED-calibration beam “off” • 3/week Full-calibration LED beam “on” +LED beam “off” • + C-W (Li) + C-W (B) + s • 1/week 24Hrs RMD 5-mixed trigger data Total of 139 TB Data Taken 2008 MEG Review February 2009

  18. Physics Data Preparation • Analysis Scheme: (Physics Analysis Working Group) • Data Reduction in form of “Pre-selection” • - use very lose cuts • “Conservative Criteria”(ensure non-biasing) • reduces data to16% of triggered events • Incorporate“Blinding” in “pre-selected” data • use “Hidden” Signal-box on parameters E& Te  • directly via MEGAnalyzerwith widths • ~ ± 4.8 MeV & ± 1.5 ns respectively • Perform Likelihood Analysis on “final revealed data” • after optimized background study outside “signal-box” •  “side-bands” • Probability Density Functions (PDFs) for Likelihood Analysis • obtained partially direct from measurement & partially from MC. • MC substantially advanced e.g. RMD + radiative corrections etc. Simulation “Blinding” Simulation MEG Review February 2009

  19. Conclusions • With a consolidated effort made by the “whole” collaboration, as well as basically • starting from ”scratch” at the beginning of the 2008 we were able to achieve our goal • of taking “True” Physics Data! • despite many detector/electronics problems that were encountered we were able to • dedicate 12 weeks out of the expected 16 weeks to “pure (MEG+RMD) Physics Data • a vast amount of calibration data was taken during the whole 2008 period which • served a as vital input to understanding encountered effects during the run • – this however will continue to serve as a basis for a better understanding of our • detector with on-going analysis • several factors concerning our hardware led to a non-optimal MEG Detector in 2008 • the main issues have been addressed ( DC: HV-stability, Calorimeter: LXe-purity, • PMT gain-stability, TC: fibre incorporation in trigger) • the most worrying issue is that of the DC HV-stability – this however is being tackled • with a large and dedicated effort by the “detector group” – the experts! and as has • been shown before, especially with “forefront” detector technology such problems • CAN BE SOLVED! • we still have a lot of work to do & a lot of improvements are still necessarybut !!! • the following “Expert” talks will show that the MEG Collaboration has • a lot of dedicated & resourceful means at it’s disposal MEG Review February 2009

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