Use of Beam Loss Monitor type detectors in CNGS muon station 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli Talk overview 1. Muon monitoring at CNGS 2. Beam Loss Monitor (BLM) as muon detector at CNGS 3. Summary 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli Muon monitoring at CNGS Main beam parameters Proton beam Target Horn He tube Reflector 2.7 43.4m 100m Decay pipe Hadron stop  detectors 1092m Fe C 18m 67m SEM foils 5m  Burst duration 10.5 s Time between 50 ms / 6 s bursts 2  Muon fluxes 1.5x104 – 4.5x107 p/cm2 x-slice (m)  / 1013pot / cm2 x107 x105 A system based on a set of fixed and movable SSD’s (like at WANF). Original proposal 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli Muon monitoring at CNGS (2) 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli Muon monitoring at CNGS (3) CNGS features and special requirements • No access to the muon chambers during the runs, minimal number of accesses during the shutdowns => detectors should be very reliable 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli Muon monitoring at CNGS (4) > 500 m 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli Muon monitoring at CNGS (5) CNGS features and special requirements • No access to the muon chambers during the runs, minimal number of accesses during the shutdowns => detectors should be very reliable • The detectors and electronics are separated by the distance of more then 500 m. => detectors signal should be high 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli Muon monitoring at CNGS (6)  CC events normalized (%) First muon chamber X (cm) Horn lateral displacement 3 mm 99.0 10.1 -0.6 6 mm 97.2 19.1 -3.5 Reflector lateral displacement 10 mm 99.6 5.7 -10.7 20 mm 98.4 14.7 -12.6 Proton beam lateral displacement 0.5 mm 100.3 7.3 1.0 mm -1.2 14.8 Proton beam angular displacement 0.5 mrad 100.0 3.7 1.0 mrad 98.7 2.3 10.4 stat 0.2 0.5 1.2  / 1013pot / cm2  / 1013pot / cm2 Aligned case Mis-aligned case 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli Muon monitoring at CNGS (7) CNGS features and special requirements • No access to the muon chambers during the runs, minimal number of accesses during the shutdowns => detectors should be very reliable • The detectors and electronics are separated by the distance of more then 500 m. => detectors signal should be high • No significant changes in the  event rate at Gran Sasso even for important misalignment of beam elements or mis-steering of the beam. => detectors resolution can be moderate • Flux variation is smooth. No need for absolute flux measurement. => detectors can be big in transversal direction • Cost limitation. => detectors should be as cheep as possible 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli BLM as muon detector (1) General parameters • sealed ionisation chamber. • widely used at CERN last 30 years. • there are about 300 BLMs around the SPS and about 3000 new BLMs will be fabricated for LHC  92 5 6 Filled with 99.9% N2 at about 1.1 bar Active volume is 1250 cm2 Bias voltage 800 – 1200 V Signal electrodes Construction All isolation is done from ceramic 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli  

Valeri Falaleev & Gianfranco Ferioli BLM as muon detector (2)  3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli BLM as muon detector (3) HV and electronics 1M + 1000V 2.2 F • collected charge is 10 times more then for SSD • 18 channels (twisted pairs) signal cable up to 1500m length • read-out is sincronized with 50 Hz • common HV powers supply for all chambers • well developed shielding scheme • a few % long term stability calibration with 127Cs (3 mCi) source 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli BLM as muon detector (3) Preliminary linearity test 2.5 s slow extraction flux from 102 to 105 p/cm2 50/50 mixture of 120 Gev protons and pions Target Proton beam Proportional Ionisation Chamber (PIC) Scintillator + PM BLM Collimator 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli BLM as muon detector (4) Week points of BLM • linearity at highest intensity (4.5x107 p/cm2 for nominal CNGS beam) - space charge limit at 4 x 107 p/cm2 (6mm gap, 1kV) - not optimized detector construction Possible solutions: better design of new LHC BLM, calibration with reference chamber • a bit much of material: difficulties for calibration and beam scan Possible solutions: better design of new LHC BLM 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli

Valeri Falaleev & Gianfranco Ferioli Summary The Beam Loss Monitor is a suitable device for CNGS muon monitoring station and can be used as both fix and movable detector. Further design work on new BLM and study of chamber characteristics are needed. 3th workshop on NBI, 14-18 March 2002 Valeri Falaleev & Gianfranco Ferioli