Diapositiva 1

1
RICH Technology F. Garibaldi Hall A
collaboration meeting Jlab June 12 2009

• PID in the SBS momentum range
• RICH technique
• aerogel RICH
• - Hermes RICH
• Using it for PR-09-018

2
N.B. in case of samples with different
population at a given separation power, the
resulting contamination of the largest populated
sample of particles in the other species will be
larger by a factor equal to the ratio between the
relative populations
3
Cherenkov Light Imaging
focusing geometry proximity focusing
Ring Imaging CHerenkov counters
Detection of Internally Reflected Cherenkov light
new direction correct the chromatic error out
4
(No Transcript)
5
CsI proximity focusing Hall A (liquid radiator)
ALICE VHMPID (CsI phot., gas radiator)
dual radiator (aerogel-gas)Hermes, focusing
Pgt 10 GeV/c
6
(No Transcript)
7
Aerogel RICH storyoptical property improvemets
vs time
A
T up to 2 ?m Hunt formula TAexp(-Ct/?4)
C
Rayleigh sc.
Absorption Clarity
Airglass (80s) A0.8
(opaque,absorbing) C0.02 ?m4/cm
(diffusing) ?Aerogel in Cher. counters
8
Improving transmittance n1.03, t1cm
total
80
96
02
undefl
02
80
deflect
year A C producer ?(0.4?m)
07 02 96 80 0.96 0.005 0.95 0.01 0.8 0.02 Novosibirsk Novosibirsk Matsushita Airglass 5 cm 4 cm 2.3 cm 1 cm
? attenuation length
9
95 T.Ypsilantis, J.Seguinot, NIMA368(1995)
96 first focalized RICH with aerogel at CERN
(R. De Leo et al,NIMA) CERN-Bari-Milan-Rome-
coll. _at_ PS-T9 beam
10
96 5cm of Matsushita aerogel, ?- 10GeV/c
one event
12.8?2.7 PMs
many events
??/? 8 / pe ??/? 2.3 / ring
11
HERMES 27.5 GeV e- long.pol on
p,d,3He-long.trans.pol 1) Gas Cherenkov DIS
(94 -97)
p,k,p

• resol. dp/p2, dqlt1 mrad PID leptons
  e98, contam. lt1

12
97 the HERMES dual radiator RICH proposal
Aerogel RICH PID
?C 3? ring resolution

• focalized R 2.2 m
• n(aerogel)1.03, ?C242 mrad
• n(C4F10) 1.00137
• Npe (aerogel) 10
• ??/?(/ring) 1.2 (4.1 / pe)
• ??(/ring) 3 mrad
• ?C?-?Ck (4GeV,n 1.03) 9 mrad

3? k/p sep. (4GeV)
13
11x11x1 cc
Dry N2 flow in aerogel!
Hydrophobic aerogel from Matsushita !
14
(No Transcript)
15
0.75 PMT ? dominant pixel contribution
16
funnels pixel contrib.even larger!
17
PMTs fired-not fired!
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22

• Readout electronics based on PCOS4, binary
  readout, (gate 50 -100 ns)
• Readout F.E. to PCOS VME Module 17.2 ms
  (indipendent on occupany, basically constant)
• 2. Readout VME Modules 10 ms
• 3. Readout speed 30 ms

23
Hermes RICH (presently at UVA) fits very well the
SBS needs Entrance window 188 x 46.4 cm2 L126 cm
24
- May 96 Feasibility test
25
T ? Cher. ?s ? photoelectrons
exp
Npe (calc.) 122
?(400 nm) 2.3cm
26
exp.- calc. angle resolution ()
HERMES
?c for single pe

• Pixel 2.3
• Mirror 0.6
• Point emiss. 0.7
• n disp. 0.5
• Chromatic 1.3
• Forw.Scatt. 0.4
• Surface 0.4
• Total (calc.)/pe 2.9
• Total (exp.)/pe 3.3
• Npe (exp.) 10

Npe 10
??/?3.3/pe
??/? 1.1 /ring
Npe10 3.3? k/p sep. (4GeV) Npe6 2.5?
k/p sep. (4GeV)
27
RICH stability 1998
qC pe
qC ring
e gt 5 GeV
qC pe
e gt 5 GeV
28
RICH stability 1999
qC pe
qC ring
e gt 5 GeV
qC pe
e gt 5 GeV
29
RICH stability 2000
qC pe
qC ring
e gt 5 GeV
qC pe
e gt 5 GeV
30
RICH stability 2004
qC pe
qC ring
e gt 5 GeV
qC pe
e gt 5 GeV
31
RICH stability 2005
qC pe
qC ring
e gt 5 GeV
qC pe
e gt 5 GeV
32
RICH stability 2006
qC pe
qC ring
e gt 5 GeV
qC pe
e gt 5 GeV
33
RICH stability 2007
qC pe
qC ring
e gt 5 GeV
qC pe
e gt 5 GeV
34
qC ring ? n (egt5GeV) plot vs day
n
35
average n (egt5GeV)
Dn 0.0003
Dn 0.0003
Dn 3 10-4 in 10 years! Dn 110-4 in the
last 5 years!
36
pe reconst.starting point distribution
e gt 5 GeV
The Hermes RICH detectorfits very well the SBS
needs
Npe
TOP
one RICH HERMES half stored to be used at Jlab !
BOTTOM
a real stable aerogel RICH !
DNpe lt 0.2 in 10 years!
37
The PhotoDetectors
HPD
MaPMT

• Bialkali Photocath. D110 mm, QE(320nm)gt20
• Overall D125 mm 82 active area
• voltage -16 KV
• Electron optics cross-focussed
• demagnification 2.3
• Anode Si pixel 1 mm x 1 mm (320x32 matrix)
• 2048 pixels, size at photocath. 2.5 x 2.5 mm2

pixels, size 2.3 x 2.3 mm2
C.DAmbrosio, RICH2007, Oct 16, 2007
38
??/?(/pe)() and Npe for HERMES
with old (t5cm L2.3 cm) and new (t4cm L4cm)
n1.03 aerogel old (1) and new
(2.5x2.5mm2 ) pixel size

• old new
• Pixel 2.3 0.3
• Mirror 0.6 0.5
• Point emiss. 0.7 0.6
• n disp. 0.5 0.5
• Chromatic 1.3 1.4
• Forw.Scatt. 0.4 0.4
• Surface 0.4 0.4
• Total (calc.)/pe 2.9 1.8
• Total (exp.)/pe 3.3 (2.0)
• Npe (calc.) 12 18
• Npe (exp.) 10 (15)
• Total /ring 1.1 (0.55)

6? k/p sep. (4 GeV)
39
RICH with Multilayer Radiators
NIM A548(2005)383

• Demonstration of principle
• 44 array of H8500 (85 effective area)

p/K separation with focusing configuration 4.8s
_at_4GeV/c
Toru Iijima, RICH2007 _at_ Trieste
40
n multilayer aerogel
monolayer multilayer
Xray density (n) meas.
41
Recent tests in Frascati by our group in coll.
with LHCb
Npe sring
Multilayer ? Single layer ?
42
aerogel RICH summary
aeroRICH CERN-test HERMES HER(new) BELLE
BELLE year 96
98 02 04 07
type foc. foc.
foc. prox. prox-2lay.s n
1.03 1.031 1.03
1.05 1.047-1.057 ? (cm)
2.3 2.3 4
4.5 5 t (cm) 5
5 4 2
2 ??/? ???(/pe) 8
3.3 (2.0) 4.5 4.6
Npe 12.8 10
(15) 6.3 10 ??/? ???(/ring)
2.3 1.1 (0.55) 1.9
1.5
43

• PR-09-018 SSA with SBS
• Measurement of the Semi-Inclusive p and K
  electro-production in DIS regime from
  transversely polarized 3He target with the SBS
  BB spectrometers in Hall A
• G. Cates, E. Cisbani, G.B. Franklin, B.
  Wojtsekhowski
• and the SBS Collaboration
• http//hallaweb.jlab.org/12GeV/SuperBigBite

44
Hadron Arm SBS

• Magnet 48D48 - 46 cm gap
• 2 Tm field integral -100 ton
• Insert for beam pipe
• GEM chambers for tracking with 70 ?m resolution
• HERMES RICH for hadron-ID
• Segmented Hadron CALO (15x15 cm2 blocks)

• Angular Resolution (p 4 GeV)
• sJ_h 0.090.59/p mrad (0.3 mrad)
• sJ_v 0.141.34/p mrad (0.4 mrad)
• Vertex Resolution 0.534.49/p mm (0.2
  cm/sinJcentral)
• Momentum resolution sp/p 0.03 p0.29 (0.4 )
• CALO Trigger Threshold 1.5 GeV (online), 2.0
  (offline)

45
Main Background from g Compton in Aerogel

• Electrons gt 2.1 MeV produce Cherenkov lights in
  aerogel
• Probability of Compton scattering for 2-5 MeV
  photons in 5 cm aerogel 3
• Compton scattering rate in aerogel (photon
  fluxabove probability) 2.3 GHz
• Mean photo-electron by electrons produced in
  aerogel 5 (10 pe in HERMES for full electron
  track)
• Additional suppression due to geometry and near
  threshold effects 0.6
• Total rate on single PMT (QE 20) 2.350.60.2
  700 kHz
• Coincidence window of 50 ns 700 kHz x 50 ns
  lt5 firing PMT occupancy

46
Challenges in large acceptance/high luminosity

• RICH PID high segmentation of photon detector
  (2000 PMT) is the optimal solution
• Expected 35 extra hits/event fromsoft photons ?
  Compton electrons in aerogel (50 ns gate
  width) ? 2-5 occupancy

Electronics based on PCOS4 Binary readout, 20 MHz
transfer bus from front-end cards to VME buffered
module Total dead time of lt30 ms ? few kHz (lt10
dead time)
47
ALICE/STAR RICH Reconstruction

• Expected 12 occupancy with ?3s p/K separation
• Performance proved by MC and STAR (3--5
  occupancy) real data.

D. Di Bari, RICH07/Trieste
According to Montecarlo JLab-HERMES-RICH should
be able to handle moderate (5) occupancy
48
Development of Cherenkov Light Imaging Techniques
is a lively and fertile field of research with
beneficial feedbacks in many other scientific
sectors. It would not have advanced to
thepresent state without Tom Ypsilantiss ideas,
enthusiasm, constructive arguments andoutstanding
achievements.
49
Backup slides
50
1) n dispersion (633 nm)
minim.deflec. l 4m ? high precision ?n/n10-4
nav1.0304 Dn310-4
?n/(n-1) 1.5 reduced to 1.0 by
sorting similar-n tiles
0.5 /pe
51
2) chromatic dispers. n (?) meas.
1.0312?0.0008
1.3 / pe
52
3) forward scattering

• due to large inhomogeneities (aC) of ?, mostly on
  the surfaces
• responsible of fuzzy vision of objects through
  aerogel
• influence dNpe/d? not Npe
• forward peaked (? Rayleigh isotropic)
• dep. on pH of solvent used in gel

aC gt ? FS
5 cm of aerogel 23 of Cher.ph. are FS _at_1.55
mrad ? ??FS
aC lt ? Rayleigh
0.4 /pe
53
4) surface irregularities
avoid internal reflectionsblack tape on lateral
surfaces


0.4 / pe
pe start point dist.
54
geometrical contributions to ??C
1) pixel
2) focal plane
a)
(??/?)opt.aber. (d/R)2 0.5
b)
?? ?/2R(??/?)surf.imp. 0.3
mirror alignment
a)b) (??/?)mirror 0.6 / pe
3) point emiss.
(??/?) point 0.7 / pe
55
aerogel opt. properties contrib.s to ??C

• 1) n dispersion in the different tiles
• 2) chromatic dispersion n(?)
• 3) forward scattering
• 4) tile surface irregularities

aerogel Selected 850 tiles over 1200 11x11x1 cc
from Matsushita 2 planes, 5 rows, 17 columns, 5
layers
one aerogel radiator
Optical characterization of n1.3 aerogel of the
HERMES RICH E.Aschenauer et al., Nucl. Instr. and
Meth. A440 (2000) 338
56
(No Transcript)
57
(No Transcript)
58
Propose to measure the SSA of SIDIS processes
n?(e,ep?)X and n?(e,eK?)X

• Extract Sivers and Collins (and Pretzelosity)
  asymmetries on p and K with high statistics
• Provide 2D binning (at least) on the relevant
  variables x, P? and z, for both hadrons
• Provide Q2 dependence
• Explore for the first time the high x valence
  region (with overlap to HERMES, COMPASS, JLab6
  data)

• Understanding of QCD dynamics in the nucleon by
  the Sivers effect
• Improve knowledge of the nucleon structure in
  terms of parton distribution functions
• Shed more light on the origin of the nucleon spin

59
Polarized SI-DIS process
60
Experimental Setup and parameters
e3He??ep(K)?X
BB e-arm at 30o ? 45 msr GEM Tracker Gas
Cherenkov Shower ? GMn/PR-09-019 SBS h-arm at
14o ? 50 msr GEM tracker excellent PID /
RICH Hadron CALO
Event rate 104HERMES 60 days of production
expected stat. accuracy 1/10 of proton HERMES
Beam 50 ?A, E8.8 and 11 GeV (80 long.
Pol.) Target 65 polarized 3He ?
GEn(2)/PR-09-016 ? Luminosity 1.41037 cm-2s-1 ,
0.05 sr
61
VHMPID
The simulation has been executed using AliRoot,
the official simulation framework of the ALICE
experiment.
Material photon transmittances and CsI
photocathode quantum efficiency
C5F12 refractive index as a function of photon
energy
RICH 2007, 16 October 2007
G. Volpe
62
Studied setup
Focusing setup the focusing properties of a
spherical mirror of radius R 240 cm, are
exploited. The photons emitted in the radiator
are focused in a plane that is located at R/2
from the mirror center, where the photon detector
is placed.
RICH 2007, 16 October 2007
G. Volpe