Design and prototype tests of the system for the OPERA spectrometers Stefano Dusini INFN sezione di Padova Outline OPERA Detector Inner Tracker Design Mechanical support Gas & HV Production and Quality Test Schedule Conclusion Institutions Involved: CERN, Frascati, Napoli, Padova, Zagreb
OPERA detector Target ν target and τ decay detector 24 a modules consisting of wall of Pb/emulsion planes of orthogonal scintillator strips bricks Muon Spectrometer µ identification measure charge and momentum beam monitoring
Muon Spectrometer Dipole Magnet + Inner Tracker θ/2 µ 8.75 m B=1.55 Tesla top view θ/2 Dipole Magnet: 6 station of vertical drift tube with 0.5 mm space resolution p p 0.5 m 1 m 2 x 12 8.75 x 8.2 m 2 and 50mm thick Fe Walls B = 1.55 Tesla 0.25 for p < 25 GeV Drift tubes 0.82 m 2 x 11 gap, 20mm thick, instrumented with muon tracking, energy by range Precision Tracker: for drift tube timing space ambiguities
for drift tube t 0 Single plane in front first two drift tube station 8.75 x 8.0 m 2 covered with 21 2.91 x 1.14 m 2 3 cm wide strip @ ±45 o ~ 3150 channel per spectrometer ~ 2ns time resolution easily achieved Cosmic telescope setup in Padova 1 (0.7x0.7 m 2 ) 3cm strip 48% Ar, 48% C 2 H 2 F 4, 4% Iso 15 m flat cable 7.7 KV Time resolution (ns) Time resolution (ns)
all other all other Cooling system of coils left / right centre to keep temp low
Stefano Dusini Design and prototype tests of the system for the OPERA spectrometers 2001, Coimbra Side view
Stefano Dusini Design and prototype tests of the system for the OPERA spectrometers 2001, Coimbra 20 mm
Isobutane line 4% parallel 14 C2H2F4 by 48% fed Ar serially is 48% row mixture: Gas Each Gas Gas connection between two s Gas in Gas out High Voltage operating in Streamer mode ~7.7KV Each chamber independently supplied 1386 HV channel Standard CAEN HV supplier + distribution box
Signal & Readout Electronics in streamer mode simple discriminator with variable threshold 32 channel VME card is under development in Padova efficiency Percentage Threshold (mv) HV= 7.7 KV HV= 7.7 KV Threshold (mv) Threshold (mv) µ! Measures made in Padova with a cosmic telescope 2 (0.7 x 0.7 m 2 ) 3 cm strip Standard Gas mixture (48% Ar, 48% C 2 H 2 F 4, 4% Iso.) Scintillator for trigger,
Performance Full GEANT3 simulation of the Inner Tracker signal modelled using beam (CERN) and laboratory (Padova) test Simulation shows resolution ~ 0.7cm with 2.6 cm strip Space resolution δx δy
Production are produced by General Tecnica (Italy) Babar production protocol N. chambers Inner Tracker 1386 XPC 126 Total 1512 packed vertically in box; 310 x 120 x 60 cm 3, 12 chambers/box. LNGS Quality test @ Lnaboratori Nazionali Gran Sasso (copying from Babar) Detail of the box packing Strip GAS leakage tests HV and chamber conditioning tests; Chamber radiography with cosmic muons. Plastic absorber
" " " " " Cosmic test @ LNGS stay vertical in the box Two walls of Glass for cosmic trigger. Top side free for access and load/unload. Horizontal readout strips mounted on site: commercial flat cables on a honeycomb support. Readout: digital on one strip side, time difference on both sides (existing electronics). Boxes cosmic µ Detail of the box packing Strips 1 m Plastic absorber
Mounting Mounting schema Mounting Magnet Wall Glue horizontal strip on spectrometer wall Each row mounted + HV cable + gas on the frame Each row mounted at once Vertical strip Test the whole plane Spacer Frame Cradle to hang on the crane Magnet wall
February 2002: start production # 20 chambers per week 6 month for 1 spectrometer # 1 plane (21 chambers) per week 6 month for 1 Cosmic test in parallel with production and installation Schedule (very tight) September 2002: start underground installation spectrometer
maximise the geometrical acceptance Low rate exp. streamer mode simple read out electronic Conclusions Large application of in OPERA spectrometers 1512 chambers of 2.91x1.14 m 2 ~ 4600 m 2 ~40000 channels read with variable threshold discriminator Way construction simplicity used also for timing