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20 .0 2 .14

LHCb MUON. Plans on GIF++ (16.65 TBq). What has been done for study of aging in MUON MWPCs and GEMs before RUN1: Six months on GIF ( 137 Cs, 675GBq of 662keV g ) in 2001 – four gap MWPC (prototype) accumulated ~0.255 C/cm of wire and 0.83 C/cm 2 of cathodes

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20 .0 2 .14

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  1. LHCb MUON. Plans on GIF++ (16.65 TBq) • What has been done for study of aging in MUON MWPCs and GEMs before RUN1: • Six months on GIF (137Cs, 675GBq of 662keVg) in 2001 – four gap MWPC (prototype) accumulated ~0.255 C/cm of wire and 0.83 C/cm2 of cathodes • - One month on Casaccia Calliope Facility with ~1,25MeVg (60Co, ~1015Bq) – four MWPCs and one GEM tested. MWPCs accumulated ~0.44C/cm of wire. In both tests no gain loss or other significant effect was detected. Oleg Maev 20.02.14 1

  2. New requirements on upgraded MUON 2013:”LHCb PID Upgrade Technical Design Report” Instantaneous luminosity of 2x1033 cm2 s-1 and for an integrated luminosity of 50 fb-1 Average deposited charge (C/cm of wire) after 50 fb-1 in the most irradiated chamber of each station and region of the muon system. 2008: “LHCb Detector at the LHC” J.Instrum.3 (2008) S08005 At a luminosity of 2x1032 cm2 s-1 the highest rates expected in the inner regions of M1 and M2 are respectively 80 kHz=cm2 and 13 kHz=cm2 per detector plane. In the detector design studies, a safety factor of 2 was applied to the M1 hit multiplicity and the low energy background in stations M2-M5 has been conservatively multiplied by a factor of 5 to account for uncertainties in the simulation. At L~2x1033 cm2s-1  ~3C/cm of wire expected at max. in 10 years (50fb-1) - M1 removed At L~2x1032 cm2s-1  ~1C/cm of wire expected at max. in 10 years - M1 in the detector Oleg Maev 20.02.14 2

  3. Plans (very preliminary) In order of priority: 1.Aging study with set of chambers from inner regions and probably with couple of chambers from outer regions in shadow – approximately 3-4 months on GIF++ in 2015. 2. Some aging study would be desirable with prototypes of high granularity detectors (new MWPCs and new GEMs) which are under design now for LS2-LS3. It depends on readiness of prototypes. Apparently, it could happened not early than in second half of 2015. 3. As a byproduct study it would be very interest to investigate on GIF++ a method for curing MUON chambers suffered with Malter currents by adding a small amount of oxygen (~0.2-2%) in the nominal Ar(40%)/CO2(55%)/CF4(5%) gas mixture with reverse polarity (negative) and at nominal HV. See first results in https://indico.cern.ch/getFile.py/access?contribId=3&resId=1&materialId=slides&confId=289760 It could be organized in shadow of 1. - optimizing the percentage of oxygen in gas mixture • test the method on number chambers suffered with Malter-currents to prove it even statistically. Oleg Maev 20.02.14 3

  4. Infrastructure Aging: • Gas: MWPCs – nominal mixture:Ar(40%)/CO2(55%)/CF4(5%) 2- 10 l/h GEM – nominal mixture: Ar(45%)/CO2(15%)/CF4(40%) 10-15 l/h - for GEM the mixture potentially could be changed a bit with reducing of CF4 • 2. HV: • MWPCs – CAEN SY2527 • GEM – INFN’s PS • 3. Environment, monitoring atm P,T, H Malter-currents study: In general, infrastructure same as for aging, just a couple of additional options: • Option for admixing a few percent (0,2 -5%) of oxygen • Very likely a picoampermeter and precise flow mass controller would be needed Oleg Maev 20.02.14 4

  5. News from GIF++ meeting Oleg Maev 20.02.14 5

  6. A. Fabich, EN-MEF-LE Schedule EDMS 1328252 V0.3 CE start Jan. 2014 • Mid May: ready for PH equipment in gas zone • Beginning June: ready for lower muon tracker • Beginning July: ready for PH/users’ equipment in bunker • Decommissioning in the West Area • March: removal of blocks upstream of GIF (no impact on operation) • August/September: secure irradiator • Autumn 2014: removal of infrastructure and concrete castle (SBA) Functional specs: -Juli 2013 Design -Dec. 2013 Infrastructure installation March-July 2014 Irradiator delivery Aug. 2014 Commissioning Sept.-Oct. 2014

  7. A. Fabich, EN-MEF-LE GIF++ layout (1) PPX (only emergency) dump Irradiation area dump secondary beam PPG service zone Preparation zone MAD cable trays to control room PPE (entrance)

  8. Supply lines for 15 gases simultaneously 40 m2 net area 8 distribution panels with each 6 return lines 17 racks for gas equipment 6 km of piping (304L / 316L) A. Fabich, EN-MEF-LE Service zone: gas (mixing) zone

  9. hosting a 137 Caesium source: 14 TBq Irradiator will be equipped with a identical filter system on both sides (up- and down-stream) A. Fabich, EN-MEF-LE Irradiator

  10. A. Polini DCS Reminder • Use PVSS/WinCC OA (as in LHC experiments) • Many components, devices, HW and SW already available (CAEN System, CAN PSU, ELMB, ENV Sensors, VME crates etc.) • CAEN Easy Power System • 1 mainframe, 1 Power Generator, 1-2 crates + with HV and LV boards(*) and 1 ADC A-3801 board for monitoring (128 channels), this includes also ENV and gas monitoring • (*) Some Low Voltage possibly external (non CAEN) with remote control via PVSS • Mainframe and PCs possibly placed proximity of the control room (non radiation area) along with DAQ PCs and equipment. • EASY crates and other equipment, more close to detector area. Counting Room AC/DC converter 48V 48V … OPC … Crate1 Crate2 Branch Controllers Mainframe HV/LV Boards HostileArea A. Polini 10 A. Polini 10

  11. Oleg Maev

  12. Preliminary conclusions In overall, infrastructure provided by GIF++ facility looks quite good for an aging test of muon chambers. Looks reasonable to use own cables and HV PSs. Number of gas mixers and distributors allows to plan most of work and even studies for MUON, but oxygen for Malter-study Proposed strategy: to be ready for an aging test of existing chambers and prototypes of high granularity detectors before second half of 2015 Some program for Malter-current study in shadow of aging test would be desirable. During preparation of this test, it would be good to continue Malter study in the PIT this year. For the control of aging test on GIF++ a WINCC OA – project would be useful. Involving additional manpower for 2015 is needed. Problem – visit’s money for this year at least. Oleg Maev 20.02.14 12

  13. Backup Oleg Maev 20.02.14 13

  14. Oleg Maev Malter effect SOURCES: Avalanche producing polymers deposits Some oxides are highly resistive. Constructions material and gas pollutants. Insulating deposits left from sparks. Corona on sharp point on the cathode. Fingerprints Etc. Necessary condition for electron emission: a) Localized primary ionization deposit. b) An insulator on the cathode. c) A rate of the charge build up is higher than its removal rate. d) Excessive field cathode gradients help to trigger it. e) To start the effect, it needs an ignition. Ignition mechanisms: a) Highly ionizing heavy ions. b) X-rays. c) Sparks. d) Sharp points on electrodes causing corona. 14

  15. Oleg Maev “Good” additive – Oxygen Oxygen ionization reactions in avalanche: e-+ O2→ O2+ +2e- e-+ O2→ 2O* + e- e-+ O2→ O2- e-+ O2→ e- + O+ + O- It well known in the Plasma Chemistry that the oxygen radicals and ions excellent reacts with organic compounds and the end product of this reaction are volatile molecules such as CO, CO2, H2O, H2 etc. which are most stable, and can be removed by gas flow Practical examples: The rate of removal of organic polymeric material can be often increased in an oxygen plasma (H. Boeing, Plasma Sci.&Tech., page 281) 1987. Cleaning of mirrors of the contaminating films by a glow discharge in oxygen plasma. (R. Gillette et al., Vac. Sci. Tech., 7 (1070) 534) Recovery from the Malter effect deposits by Oxygen (A. Boyarski – BaBar R&D study) 2001. Inverted HV 15

  16. Oleg Maev Scanning the CMB with radioactive sources Beam in 2012: J~0.1 nA/cm2 Scanning with source Am241 (J~0.3 nA/cm2) - no visible effect Scanning with Sr90- J~70 nA/cm2 ignited the Malter current in two places in GAP A 16

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