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

2. 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
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3. 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: ×10-10(BNL E787/E949)
Very hard from exp.point of view: one charged track (a pion) and nothing else!!
+1.15
-1.05
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4. 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
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5. 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
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6. 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
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7. 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
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8. 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
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9. 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.)
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10. 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
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11. THE MIRRORS– FRONT VIEW
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12. STABILIZING RIBBONS & MIRROR SUPPORTS – FRONT VIEW
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13. THE HOLES ON THE SUPPORTING HONEYCOMB PANELS – FRONT VIEW
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14. THE TENSIONING RIBBONS – REAR VIEW
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15. The Photomultipliers Hamamatsu R7400U-03 UV-glass, bialkali, 8 dyn
16 mm wide (8 mm active)
Gain 1.5 V
280 ps time jitter (FWHM)
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
M.Lenti

16. 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
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17. 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
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18. 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
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19. Test Beams Strong RD to validate the chosen approach with prototypes
NIM A 593 (2008)
NIM A 621 (2010)
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,…)
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20. RICH400: performances NIM A 593 (2008) 314-318
pions
pions
pions
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21. 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
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22. SPARES
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23. 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
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24. THE HALF CENTRAL MIRROR
TWO DOWELS
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25. THE HALF CENTRAL MIRROR
TENSIONING RIBBON
(HORIZONTAL AXIS ROTATION)
SLIDING DOWEL SYSTEM
(VERTICAL AXIS ROTATION)
MIRROR SUPPORT
M.Lenti

26. THE SLIDING DOWEL SYSTEM - DETAIL
KNOB SUPPORT
FIXED DOWEL
KNOB
ACTUATING BAR
SLIDING DOWEL
MIRROR SUPPORT
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27. THE HALF MIRROR IN PLACE
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28. 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
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29. RICH-100 Prototype 2007 Test Beam
96 PMT
Mirror f=17 m
p- p=200 GeV/c (SPS)
CERN Cavern ECN3
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30. RICH-100: 2007 Test Beam results
NHits ≈ 17
DtEvent ≈ 70 ps
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31. RICH-100: results
Dqc≈ 50 mrad
DtEvent ≈ 70 ps
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32. RICH-400: 2009 test beam 414 PMT + FE and DAQ , cooling
Pions at tunable energy
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33. RICH-400: fitted rings 20 GeV/c Hard to reconstruct ring… positrons
pion
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34. 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
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35. 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)
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36. RICH 400: results Paper submitted to NIM on April 23, 2010 9.10.2013
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