a detector for ( m)erhic
DESCRIPTION
A Detector for ( M)eRHIC. Detector Requirements from Physics. ep -physics the same detector needs to cover inclusive ( ep -> e’X ), semi-inclusive ( ep -> e’hadron(s)X ) and exclusive ( ep -> e’p p ) reactions large acceptance absolutely crucial (both mid and forward-rapidity) - PowerPoint PPT PresentationTRANSCRIPT
EIC-IAC @ JLab, November 2009 1
A Detector for (M)eRHIC
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 2
Detector Requirements from Physics
E.C. Aschenauer
ep-physics the same detector needs to cover inclusive (ep -> e’X),
semi-inclusive (ep -> e’hadron(s)X) and exclusive (ep -> e’p ) p reactions
large acceptance absolutely crucial (both mid and forward-rapidity) particle identification is crucial
e, p, K, p, n over wide momentum range and scattering angle excellent secondary vertex resolution (charm)
particle detection to very low scattering angle around 1o in e and p/A direction
in contradiction to strong focusing quads close to IP
small systematic uncertainty for e/p polarization measurements
very small systematic uncertainty for luminosity measurement
eA-physics requirements very similar to ep
challenge to tag the struck nucleus in exclusive and diffractive reactions.
EIC-IAC @ JLab, November 2009 3
Event kinematics scattered lepton
E.C. Aschenauer
DIS
DIFFRACTIVE
4x50 4x250
175o
20x250
179o
withoutmagneticfield
EIC-IAC @ JLab, November 2009 4
Event kinematics produced hadrons (p+)
E.C. Aschenauer
DIS
DIFFRACTIVE
4x504x25020x250
withoutmagneticfield
DIS:smalltheta important
EIC-IAC @ JLab, November 2009 5E.C. Aschenauer
Include:recoil proton plots and update the other ones for better visibility
EIC-IAC @ JLab, November 2009E.C. Aschenauer
6
STAR
PH
EN
IX
2 x 200 m SRF linac4 (5) GeV per pass5 (4) passes
Polarized e-gun
Beamdump
4 to 5 vertically separatedrecirculating passes
Cohere
nt
e-c
oole
r
5 mm
5 mm
5 mm
5 mm
20 GeV e-beam
16 GeV e-beam
12 GeV e-beam
8 GeV e-beam
Com
mon
vacu
um
ch
am
ber
Gap 5 mm total0.3 T for 30 GeV
eRHICdetector
MeRH
IC
dete
ctor
10-20 GeV e x 325 GeV p 130 GeV/u Au
possibility of 30 GeV @low current operation
ERL-based eRHIC Design
EIC-IAC @ JLab, November 2009 7
A Detector for Diffraction
E.C. Aschenauer
e
p
HadronicCalorimeter
EM Calorimeter
Si tra
ckin
g
stat
ions
Compact – fits in dipole magnet with inner radius of 80 cm.Long - |z|5 m
Design by Allen Caldwell:
2x14 Si tracking stations
EIC-IAC @ JLab, November 2009 8
First ideas for a detector concept
E.C. Aschenauer
Dipol3Tm
Dipol3Tm
Solenoid (4T)
ZDC
FPD
FED// //
Dipoles needed to have good forward momentum resolution Solenoid no magnetic field @ r ~ 0
DIRC, RICH hadron identification p, K, p high-threshold Cerenkov fast trigger for scattered lepton radiation length very critical low lepton energies
EIC-IAC @ JLab, November 2009 9
IR-Design for MeRHIC I @ IP-2
E.C. Aschenauer
no synchrotron shielding included IP-2: height beam-pipe floor ~6’ (with digging
~10’)
EIC-IAC @ JLab, November 2009 10
Diffractive events
E.C. Aschenauer
include 1 or 2 slides from Matt on diffractive studies for eA to make thepoint where the nuclei go, like Thomas slide 19
EIC-IAC @ JLab, November 2009 11
Detection from hadron beam fragments
Tagging from Au fragments and p/n in ep suppress incoherent scattering / ensure exclusivity
neutrons are detected in ZDC protons use magnetic rigidity Au:p 2.5:1
DX magnets disturbs p tagging
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 12
IR-Design for MeRHIC IP-2
E.C. Aschenauer
no synchrotron shielding included allows p and heavy ion decay product tagging IP-2: height beam-pipe floor ~6’ (with digging ~10’)
EIC-IAC @ JLab, November 2009 13
First ideas for a detector concept
E.C. Aschenauer
Dipol3Tm
Dipol3Tm
Solenoid (4T)
ZDC
FPD
FED// //
Dipoles needed to have good forward momentum resolution Solenoid no magnetic field @ r ~ 0
DIRC, RICH hadron identification p, K, p high-threshold Cerenkov fast trigger for scattered lepton radiation length very critical low lepton energies
EIC-IAC @ JLab, November 2009 14
Basis for Detector design
E.C. Aschenauer
explain the basis for the detector design, like dirc copy of Babar ….
EIC-IAC @ JLab, November 2009 15
Drift Chambers central trackingala BaBar
MeRHIC Detector in Geant-3
E.C. Aschenauer
no hadronic calorimeter in barrel, because of vertical space @ IP-2
Silicon Stripdetector
EIC-IAC @ JLab, November 2009 16
MeRHIC Detector in Geant-3
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 17
MeRHIC Detector in Geant-3
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 18
Summary
Have done first steps on a detector design Optimizations needed
magnetic fieldsdo we need 4T for solenoid and 3Tm for dipole
what radiation length can we tolerate @ low e’ momentum
optimize distance Dipole to Solenoid impact of beam lines through the detector on physics
need to optimize acceptance at low scattering angleneed acceptance down to 1o
need to include lepton polarimeter in IR design need to include luminosity monitor into IR design
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 19
Start immediately at 12o’clock
E.C. Aschenauer
Detector cost savingshave MeRHIC-detector @ IP-12
fully staged detector from MeRHIC to eRHIC vertical space much bigger need to buy magnets only once can stage detector components, i.e. hadronic calorimeter no moving of components
only advantages
EIC-IAC @ JLab, November 2009 20
12:00 experimental area
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 21E.C. Aschenauer
Work done @ JLAB
EIC-IAC @ JLab, November 2009 22
ions
electrons
solenoid dipole bendingscattered protons “up”
IP withcrossing angle electron FFQs
ion FFQs
Distance from IP to electron FFQ: 6 m to ion FFQ: 9m
Electron FF quad
Distance from IP
length Field strength
Beam size sx
@ 3 GeV
Beam size sy
@ 3 GeV
Quad 1 6.0 meter 50 cm -1.14 kG/cm
5 mm 4 mm
Quad 2 6.75 meter
120 cm 0.71 kG/cm
8 mm 3 mm
Quad 3 8.7 meter 50 cm -0.75 kG/cm
4 mm 4 mm
Modest electron final focusing quad field requirements quads can be made small
ELIC Detector/IR Layout
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 23
8 meters (for scale)
140 degrees
Tracking
TOF
dipole
solenoid
RICH
ECAL
DIRC
HCAL
HTCC
Offset IP?
Ion beame beam
dipole1st (small) electron FF quad @ 6 m
ELIC detector cartoon - Oct. 09
E.C. Aschenauer
Additional electron detection (tracking, calorimetry) for low-Q2 physics not on cartoon
EIC-IAC @ JLab, November 2009 24
Central 4T solenoid with 5 meter length and 4 meter ID Need to add good particle identification detectors up to 40 degrees on ion side drives large ID to keep this area “open” 4T field renders O(1%) or better momentum resolution for particles with momentum < 10 GeV (and angles > 40 degrees)
Optimize detector to detect particles down to (at least) one degrees Add 2-3 Tm dipole field to improve momentum resolution at forward angles. Two solutions: add dipole, or add dipole to solenoid? Can in principle also have split dipole, with different polarity before/after IP, if this helps accelerator design.
5T solenoid with 0.6T dipole winding:Integrated transverse (By) field strength
@ 90 degrees 10.9 Tm@ 40 degrees 15.3 Tm@ 1 degree 1.4 Tm
May present alternate solution if space is at a premium & 1.4 Tm sufficient field strength at 1o.
Note: all configurations iron free at moment
Dipole coils
ELIC Detector Magnetic Field
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 25
kk'
ZP ZP'
q'
qMm
e + AZ e + AZ + (,,J/)Determining exclusivity requires tagging the nucleus in the final state. The typical scale of transverse momentum transfer is given by the rms nuclear radius.
(for nuclei from 4He to 20Ne, this scale ranges from 125 MeV/c to 75 MeV/c)
Recoil Tagging in Deeply Virtual Exclusive Reactions on Nuclei
E.C. Aschenauer
For Nuclei ≥ 4He, the recoil nucleus is – INSIDE the transverse admittance of the FF Quads
• Qms ≈ 1 mr PA,transverse ≈ Z·(60 MeV/c) (for 60 GeV ion beam)
• Beam spread is larger than 1/RA scale for nuclear imaging.
• Z·(60 MeV/c ) > (0.2 GeV/c)/A1/3 (≥75 MeV/c for AZ< 20Ne) – OUTSIDE the longitudinal admittance of the ring lattice!!!
The nuclei may be detectable at high resolution with far forward tracking in the lattice by having large dispersion ELIC study
EIC-IAC @ JLab, November 2009 26
Far Forward Ion Tagging at (60 GeV/c) Z
Sample optics at token Roman Pot Telescope position ELIC typical: Dispersion D = 1 m, Beta function b* = 2 m ELIC typical: (x,Q) = (250 mm, 125 mr) rms Use a 10sx Beam Stay Clear (BSC) distance 2.5 mm Ions are detectable for |dPA||/PA| > BSC/D = 2.5 x 10-3.
Skewness 2z (~x/A) of Deep Virtual reaction = long. momentum fraction of a nucleon in projectile ion.Skewness acceptance: 2z > (2.5x10-3)A 0.05 for 20Ne.
Assumption: 1 m drift with 100 mm spatial resolution dQ = 100 mr equal to beam Qrms. PA’ Momentum Resolution = sx/D = 2.5 x 10-4.
D|| = (k-k’-q’) || = (PA’-PA’)|| s(D||) = (4 x 10-4)(30 GeV/c) A = (12 MeV/c) A
Exclusivity constraint D2 = 2MA (PA’-PA) Using ELIC arc as spectrometer to a longitudinal
momentum transfer resolution of 10-4 by increasing dispersion @ IR will be explored in more detail
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 27E.C. Aschenauer
BACKUP
EIC-IAC @ JLab, November 2009 28
Zeus @ HERA I
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 29
Zeus @ HERA II
E.C. Aschenauer
EIC-IAC @ JLab, November 2009 30
Hera I vs Hera II
E.C. Aschenauer
Focusing Quads close to IPProblem for forward acceptance