LHCb MUON. Plans on GIF++ (16.65 TBq) Oleg Maev What has been done for study of aging in MUON MWPCs and GEMs before RUN1: -Six months on GIF ( 137 Cs, 675GBq of 662keV  ) in 2001 – four gap MWPC (prototype) accumulated ~0.255 C/cm of wire and 0.83 C/cm 2 of cathodes - One month on Casaccia Calliope Facility with ~1,25MeV  ( 60 Co, ~10 15 Bq) – 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.

New requirements on upgraded MUON Oleg Maev 2008: “LHCb Detector at the LHC” J.Instrum.3 (2008) S08005 At a luminosity of 2x10 32 cm 2 s -1 the highest rates expected in the inner regions of M1 and M2 are respectively 80 kHz=cm 2 and 13 kHz=cm 2 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. 2013:” LHCb PID Upgrade Technical Design Report” Instantaneous luminosity of 2x10 33 cm 2 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. R1R2R3R4 M M M M At L~2x10 32 cm 2 s -1  ~1C/cm of wire expected at max. in 10 years - M1 in the detector At L~2x10 33 cm 2 s -1  ~3C/cm of wire expected at max. in 10 years (50fb -1 ) - M1 removed

Plans (very preliminary) Oleg Maev 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 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 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 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.

Infrastructure Oleg Maev Aging: 1.Gas: MWPCs – nominal mixture:Ar(40%)/CO2(55%)/CF4(5%) l/h GEM – nominal mixture: Ar(45%)/CO2(15%)/CF4(40%) 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: 1.Option for admixing a few percent (0,2 -5%) of oxygen 2.Very likely a picoampermeter and precise flow mass controller would be needed

News from GIF++ meeting Oleg Maev

Schedule 6 12/02/2014A. Fabich, EN-MEF-LE EDMS V0.3 Functional specs: -Juli 2013 Functional specs: -Juli 2013 Design -Dec Design -Dec CE start Jan CE start Jan Infrastructure installation March-July 2014 Infrastructure installation March-July 2014 Irradiator delivery Aug Irradiator delivery Aug Commissioning Sept.-Oct 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)

GIF++ layout (1) 7 12/02/2014A. Fabich, EN-MEF-LE dump secondary beam PPE (entrance) MAD PPG PPX (only emergency) dump service zone Preparation zone cable trays to control room Irradiation area

Service zone: gas (mixing) zone 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) 12/02/2014A. Fabich, EN-MEF-LE

Irradiator 9 hosting a 137 Caesium source: 14 TBq Irradiator will be equipped with a identical filter system on both sides (up- and down-stream) 30/1/2014A. Fabich, EN-MEF-LE

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. 10A. Polini 10 Mainframe OPC Branch Controllers HV/LV Boards Crate1Crate2 … AC/DC converter 48V … Hostile Area Counting Room A. Polini Gif++ CERN February 12th 2014 A. Polini

Oleg Maev

Preliminary conclusions Oleg Maev 1.In overall, infrastructure provided by GIF++ facility looks quite good for an aging test of muon chambers. 2.Looks reasonable to use own cables and HV PSs. 3.Number of gas mixers and distributors allows to plan most of work and even studies for MUON, but oxygen for Malter-study 4.Proposed strategy: to be ready for an aging test of existing chambers and prototypes of high granularity detectors before second half of Some program for Malter-current study in shadow of aging test would be desirable. 6.During preparation of this test, it would be good to continue Malter study in the PIT this year. 7.For the control of aging test on GIF++ a WINCC OA – project would be useful. 8.Involving additional manpower for 2015 is needed. 9.Problem – visit’s money for this year at least.

Backup Oleg Maev

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. Ignition mechanisms: a) Highly ionizing heavy ions. b) X-rays. c) Sparks. d) Sharp points on electrodes causing corona. 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. 14

Oleg Maev “Good” additive – Oxygen Oxygen ionization reactions in avalanche: e - + O 2 → O e - e - + O 2 → 2O* + e - e - + O 2 → O 2 - e - + O 2 → 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, CO 2, H 2 O, H 2 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) 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) Inverted HV

Oleg Maev Scanning the CMB with radioactive sources Scanning with Sr 90 - J~70 nA/cm 2 ignited the Malter current in two places in GAP A Scanning with source Am 241 (J~0.3 nA/cm 2 ) - no visible effect 16 Beam in 2012: J~0.1 nA/cm 2