Progress of the NA62 RICH detector Siena 2013 13° Topical Seminar on Innovative Particle and Radiation Detectors (IPRD13) 7-10 October 2013 Siena, Italy Progress of the NA62 RICH detector On behalf of INFN&Univ Perugia INFN&Univ Firenze CERN M.Lenti INFN Sezione di Firenze

Outlook NA62: the Rare Kaon Decay Experiment at CERN The NA62 RICH The Vessel and the Gas system The Mirrors The Photomultipliers FE and DAQ 2007 and 2009 test beams: results Conclusions 9.10.2013 M.Lenti

The NA62 Experiment at CERN NA62 aim at a 10% measurement of the BR(K+→p+) Theory: BR = (0.85±0.07)×10-10 (very small th.error!!) Present result: 1.73 ×10-10(BNL E787/E949) Very hard from exp.point of view: one charged track (a pion) and nothing else!! +1.15 -1.05 9.10.2013 M.Lenti

The NA62 Layout 750 MHz primary Hadron beam at 75GeV/c 6% are Kaons 7-10 MHz of Muon Rate in the Detectors SAV Small Angle g Veto LAV: Large Angle Photon Veto Vacuum Tank CHOD Charged Hodoscope CHANTI Charged Particle Veto Target RICH KTAG Beam Pipe Measure Kaon: Time Angles Momentum GTK LKr MUV RICH Straw Tracker Decay Region 65m Total Length 270m 9.10.2013 M.Lenti

Background n.1: K+→m+n GTK + STRAWS MUV RICH Km2 :largest BR: 63.4% |PK|=75 GeV/c p qKp K+ n Km2 :largest BR: 63.4% Need ~10-12 rejection factor Kinematics: 10-5 Muon Veto: 10-5 Particle ID: 10-2 n m2miss=(PK-Pp)2 GTK + STRAWS MUV RICH 15<|Pp|<35 GeV/c Match a track (pion) seen by the STRAWS (10 MHz) with a track (kaon) seen by the GTK (750 MHz) Wrong matching: wrong missing mass Measure the track time, both upstream and downstream at 100 ps level 9.10.2013 M.Lenti

The NA62 RICH Detector Mirror mosaic Flanges with 2 x 1000 PMts Length > 17 m; Ø = up to 4m INFN&Univ Perugia INFN&Univ Firenze CERN Filled with Neon Gas at 1 atm. Beam Pipe 9.10.2013 M.Lenti

The RICH Vessel Conical cap: Support collars Part of one section. 17 m long vessel in construction steel, vacuum proof max overpressure: 150 mbar 4 m wide (beginning), 3.4 m wide (end) 4 cylindrical sections (“drums”) and one conical cap beam pipe (Ø 157 mm) going through thin aluminium entrance and exit windows 9.10.2013 M.Lenti

The Gas System Vessel volume: 200 m3 Neon at slightly above atmospheric pressure Neon density stability < 1% Contaminants < 1% The vessel is first fully evacuated Then fresh Neon is introduced in the vessel At the end the vessel is valve closed 9.10.2013 M.Lenti

The Mirrors Mirror Assembly 18 hexagonal mirrors (700 mm wide, 25 mm thick) 2 half mirrors around the beam pipe. Mirror Parameters + Quality: Spherical mirrors f= 17±0.1 m Reflectivity > 90% (195 – 650nm) Do≤ 4mm (circle which collects 90% of the reflected light.) 9.10.2013 M.Lenti

The Mirrors Alignment The orientation of the mirrors is remotely adjustable using piezo-motors Aluminum ribbons 200 mm thick and 10 mm wide are used MIRROR SUPPORT DOWEL Mirror Support Prototype Each mirror is supported by means of a dowel inserted in a hole drilled in the back of the mirror A third purely vertical ribbon is used to avoid mirror rotation Piezo Motors 20 Newtons 35 mm range 70 nm resolution LIGHTER TRANSMISSION SUPPORT 9.10.2013 M.Lenti

THE MIRRORS– FRONT VIEW 9.10.2013 M.Lenti

STABILIZING RIBBONS & MIRROR SUPPORTS – FRONT VIEW 9.10.2013 M.Lenti

THE HOLES ON THE SUPPORTING HONEYCOMB PANELS – FRONT VIEW 9.10.2013 M.Lenti

THE TENSIONING RIBBONS – REAR VIEW 9.10.2013 M.Lenti

The Photomultipliers Hamamatsu R7400U-03 UV-glass, bialkali, 8 dyn 16 mm wide (8 mm active) Gain 1.5 10+6 @900 V 280 ps time jitter (FWHM) 185-650 nm response (420 nm peak) Q.E. around 20% on peak PM output (1 p.e.): 240 fC, peak at 200 mA or -10 mV (50 ) Rise time: 0.78 ns, fall time1.6 ns 9.10.2013 M.Lenti

The PMs, cont’d 976 PMs packed per spot (18 mm min dist.) Light collection: Winston cones with aluminized mylar foil Quartz window to separate Neon from air O-rings for light tightness and thermal contact 9.10.2013 M.Lenti

The PM, III Neon-air separation disk PM lodging disk PM “face” side Quartz window side PM “rear” side: detail Few PMs inserted Detail of Winston Cones with and w/o Mylar foils Detail of a quartz window 9.10.2013 M.Lenti

Front-End and DAQ FE+DAQ contribution < 50 ps NINO ASIC (from ALICE) as fast discriminator operated in Time over Threshold HPTDC (developed at CERN) embedded on TEL62 boards (evolution from LHCb TELL1) RICH used in the Level-0 trigger of NA62 9.10.2013 M.Lenti

Test Beams Strong RD to validate the chosen approach with prototypes NIM A 593 (2008) 314-318 NIM A 621 (2010) 205-211 Test Beams Strong RD to validate the chosen approach with prototypes 2007 Test Beam: RICH proto 96 PMs (time resolution, n.of p.e.) 2009 Test Beam: RICH proto 414 PMs (3s p-m separation, DAQ,…) 9.10.2013 M.Lenti

RICH400: performances NIM A 593 (2008) 314-318 pions pions pions 9.10.2013 M.Lenti

Conclusions The NA62 RICH is a far demanding object Strong RD validated the project Installation schedule: Nov 2013: RICH vessel delivery Jun 2014: Mirrors Installation completed Aug 2014: PM installation completed Sep 2012: Gas filling completed Oct 2014: RICH commissioning and first physics run of NA62 9.10.2013 M.Lenti

SPARES 9.10.2013 M.Lenti

Kinematics 92% K+ decays 8% K+ decays PK : beam spectrometer qKp K+ n n m2miss=(PK-Pp)2 92% K+ decays 8% K+ decays PK : beam spectrometer Pp : straw chambers spectrometer 9.10.2013 M.Lenti

THE HALF CENTRAL MIRROR TWO DOWELS 9.10.2013 M.Lenti

THE HALF CENTRAL MIRROR TENSIONING RIBBON (HORIZONTAL AXIS ROTATION) SLIDING DOWEL SYSTEM (VERTICAL AXIS ROTATION) MIRROR SUPPORT 9.10.2013 M.Lenti

THE SLIDING DOWEL SYSTEM - DETAIL KNOB SUPPORT FIXED DOWEL KNOB ACTUATING BAR SLIDING DOWEL MIRROR SUPPORT 9.10.2013 M.Lenti

THE HALF MIRROR IN PLACE 9.10.2013 M.Lenti

RICH prototype 17 m long, 0.6 m wide cylindrical vessel 17 m focal, 0.5 m wide mirror 96(2007) or 414(2009) PM Vessel evacuated, then Neon filled Prototype placed along the old NA48 beam line at CERN 9.10.2013 M.Lenti

RICH-100 Prototype 2007 Test Beam 96 PMT Mirror f=17 m p- p=200 GeV/c (SPS) CERN Cavern ECN3 9.10.2013 M.Lenti

RICH-100: 2007 Test Beam results NHits ≈ 17 DtEvent ≈ 70 ps 9.10.2013 M.Lenti

RICH-100: results Dqc≈ 50 mrad DtEvent ≈ 70 ps 9.10.2013 M.Lenti

RICH-400: 2009 test beam 414 PMT + FE and DAQ , cooling Pions at tunable energy 9.10.2013 M.Lenti

RICH-400: fitted rings 20 GeV/c Hard to reconstruct ring… positrons pion 9.10.2013 M.Lenti

RICH-400: p-m separation Easy to have a good pion beam, not a muon one For each energy point, take two runs: One at the same nominal energy One at energy×mp/mm (pion velocity equal to muon velocity at nominal energy) Compare the two distributions of the fitted Cherenkov Rings GeV/c 9.10.2013 M.Lenti

RICH-400: results 15 GeV/c e m p p×mp/mm Ring Radius (mm) 35 GeV/c p e Muon suppression (15-35 GeV/c): 0.7% p×mp/mm Ring Radius (mm) 9.10.2013 M.Lenti

RICH 400: results Paper submitted to NIM on April 23, 2010 9.10.2013 M.Lenti