Preliminary Detector Design Preliminary Detector Design for the EIC at JLabfor the EIC at JLab
Pawel Nadel-TuronskiPawel Nadel-TuronskiJefferson Lab, Newport News, VAJefferson Lab, Newport News, VA
EIC Detector Workshop at JLab, 4-5 June 2010EIC Detector Workshop at JLab, 4-5 June 2010
4-5 June 2010 EIC Detector Workshop at JLab 2
Outline
1. Introduction1. Introduction
2. Interaction Region2. Interaction Region
3. Detector Requirements and Challenges3. Detector Requirements and Challenges
4. Brief Overview of Current Detector Ideas4. Brief Overview of Current Detector Ideas
4-5 June 2010 EIC Detector Workshop at JLab 3
Why a collider?
• s = 4EeEp for colliders (e.g., 4 x 9 x 60 = 2160 GeV2)
• s = 2EeMp for fixed target experiments (e.g., 2 x 11 x 0.938 = 20 GeV2)
• Unpolarized FOM = Rate = Luminosity · Cross Section · Acceptance• Polarized FOM = Rate · (Target Polarization)2 · (Target Dilution)2
• No dilution and high ion polarization (also transverse)• No current (luminosity) limitations, no holding fields (acceptance)• No backgrounds from target (Møller electrons)
Easier to reach high CM energies (EEasier to reach high CM energies (Ecmcm22 = s) = s)
Spin physics with high figure of meritSpin physics with high figure of merit
Easier detection of reaction productsEasier detection of reaction products• Can optimize kinematics by adjusting beam energies
– Laws of physics do not depend on reference frame, but measured uncertainties do!• More symmetric kinematics improve acceptance, resolution, particle identification, etc• Access to neutron structure with deuteron beams through spectator tagging (pp ≠ 0)
4-5 June 2010 4EIC Detector Workshop at JLab
Past and future e-p and e-A colliders
HERA, Hamburg, 1992-200727 GeV e on 920 GeV p, L = 5 x 1031
LHeC, CERN, Geneva
Brookhaven, Upton, NYJefferson Lab, Newport News, VA
EIC
4-5 June 2010 5EIC Detector Workshop at JLab
Kinematic coverage
• Medium-energy EIC– Overlaps with and is complementary to the LHeC (both JLab and BNL versions)– Overlaps with JLab 12 GeV (JLab version with moderate ring size)– Provides high luminosity and excellent polarization for the range in between
• Currently only low-statistics fixed-target data available in this region
-
x
Medium-energy EIC (JLab version)
s (CM energy)
Q2 ~ xys
4-5 June 2010 EIC Detector Workshop at JLab 6
Lum
inos
ity [
cm-2 s-1
]
1035
1034
1033
1032
10 100 1000 10000 100000
COMPASS
JLAB6&12
HERMES
ENC@GSI
(M)EIC
MeRHIC
DIFFDIS
EWDES
JETSSIDIS
s [GeV2]
C. Weiss
s
R. Ent
Physics and luminosity
• Right plot (L vs. s) is a projection on the diagonal of the left one (Q2 vs. x)
4-5 June 2010 7EIC Detector Workshop at JLab
• MEIC = EIC@JLAB– 1-2 high-luminosity detectors
• Luminosity ~ 1034 cm-2s-1
• Low backgrounds
– Special detector?
• ELIC = high-energy EIC@JLab– Future upgrade?
< 1 km circumference
Note: RHIC is 3.8 km
1.4 km circumference
Electron energy: 3-11 GeV
Proton energy: 20-60 GeV
s = 250 - 2650 GeV2
Can operate in parallelwith fixed-target program
MEIC@JLab – Detector Layout
Special IP?
4-5 June 2010 EIC Detector Workshop at JLab 8
Hadronic background – a comparison with HERA
• Dominated by interaction of beam ions with residual gas• Worst case at maximum energy
• Distance from arc to IP: 40 m / 120 m = 0.33• Average hadron multiplicity: (2640 / 100000)1/4 = 0.4• p-p cross section (fixed target): σ(60 GeV) / σ(920 GeV) = 0.7• At the same current and vacuum, MEIC background is 10% of HERA
Random backgroundRandom background
Comparison of MEIC (11 on 60 GeV) and HERA (27 on 920 GeV)Comparison of MEIC (11 on 60 GeV) and HERA (27 on 920 GeV)
Hadronic background not a major problem for the MEICHadronic background not a major problem for the MEIC
• With HERA vacuum, the MEIC would at 60 GeV and 1 A have backgrounds like HERA at 0.1 A– But good vacuum is much easier to maintain in a short section of a small ring!
• MEIC luminosity is also about 100 times higher (depending on kinematics)• Signal-to-background will be considerably better at the MEIC
4-5 June 2010 EIC Detector Workshop at JLab 9
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20 GeV
Q1 G[T/m] = -32 to -97Q2 G[T/m] = 22 to 67Q3 G[T/m] = -21 to -63
Gradients: 20 - 60 GeV
Ion quadrupole apertures and the minimum energy
Beam size (σ): up to 5 mmAperture (r): 10-15 σPeak field (rG): up to 5-7T
σ [c
m]
β [m
]
• Beam size: σ = √(ε β m / p)• Focal length: f = √(β* βmax)
• Quad gradient: G ~ p / f• Peak field: rG
• Emin ~ √(Emax) / β*
• Max aperture size ~ 1 / G ~ 1 / Emax
• Max beam size ~ 1 / √(β* Emin)
4-5 June 2010 EIC Detector Workshop at JLab 10
1. Luminosity at high energy1. Luminosity at high energy
2. Luminosity at low energy2. Luminosity at low energy
3. Effective low-energy operation requires f3. Effective low-energy operation requires fRFRF ~ 1 GHz ~ 1 GHz
• Naïve scaling:Luminosity ~ Ie Ip / β*
• Ep scaling due to Lorentz boost is often shown, but is not always a good approximation
Trigger, accelerator RF, and luminosity
• “Hourglass effect” requires that the bunch length L = β*• Due to “space charge”, in rings with large circumference C one has:
– Ip ~ fRF L / C = fRF β* / C, and Ie = constant
• Luminosity ~ fRF / C
• Cannot trigger on each bunch crossing as in hadron machines!• The solution is an asynchronous electron trigger
4-5 June 2010 EIC Detector Workshop at JLab 11
1. Mainly driven by exclusive physics1. Mainly driven by exclusive physics
2. But not only ...2. But not only ...
3. More details in workshop reports tomorrow!3. More details in workshop reports tomorrow!
• Hermeticity (also for hadronic reconstruction methods in DIS)• Particle identification (also SIDIS)• Momentum resolution (kinematic fitting to ensure exclusivity)• Forward detection of recoil baryons (also baryons from nuclei)• Muon detection (J/Ψ)• Photon detection (DVCS)
Detector requirements
• Very forward detection (spectator tagging, diffractive, coherent nuclear, etc)• Vertex resolution (charm, strangeness)• Hadronic calorimetry (jet reconstruction)
4-5 June 2010 12EIC Detector Workshop at JLab
Diffractive and (SI)DIS mesons4 on 250 GeV4 on 50 GeV
diffr
activ
eD
IS
• Both reactions produce high-momentum mesons at small angles
• This constitutes the background for exclusive reactions!
(no cuts)
• This constitutes the background for exclusive reactions!
4-5 June 2010 EIC Detector Workshop at JLab 13
Low Q2 (J/Ψ) vs high Q2 (light mesons) – 4 on 30 GeVrecoil baryonsscattered electronsmesons
no Q
2 cut
Q2 >
10
GeV
2
t-distribution unaffected
forward mesons: low Q2, high p
low-Q2 electrons in electron endcap
high-Q2 electrons in central barrel:
1-2 < p < 4 GeV
mesons in central barrel:
2 < p < 4 GeV
Tanja Horn
4-5 June 2010 EIC Detector Workshop at JLab 14
Exclusive light meson kinematics (Q2 > 10 GeV2)
Tanja Horn
recoil baryonsscattered electronsmesons
4 on
250
GeV
4 on
30
GeV
Θ ~ √t/Ep
PID challenging
very high momenta
electrons in central barrel, but p different
0.2° - 0.45°
0.2° - 2.5°
ep → e'π+n
4-5 June 2010 EIC Detector Workshop at JLab 15
1. Central Detector1. Central Detector
2. Forward hadron detection2. Forward hadron detection
3. Low-Q3. Low-Q22 electron tagging electron tagging
• Particle ID (e/π/K/p)• Momentum resolution (tracker radius / layout)
Main detector challenges
• Acceptance (3 stages needed)• Momentum resolution at intermediate angles (0.5-5°)
• Endcap design (DIRC readout?)• Common dipole for both beams?
4. Integration with accelerator4. Integration with accelerator
4-5 June 2010 EIC Detector Workshop at JLab 16
Three stage forward detection strategy
• Charged particle tracking resolution in a solenoidal field becomes very poor at small angles (up to 5-10°)
– F = v x B• A crossing angle of 3-5° between the ion beam and
solenoid axis moves this spot to a peripheral point in φ– Good place for (very small) electron quads
• A crossing angle also allows a downstream analyzing magnet with comparable aperture (3-5°)
• High-momentum particles scattered at angles < 0.5° can be detected after passing through the ion quads
solenoid
electron FFQs3-5°
0°
analyzing magnet with detectors
ions
electrons
IP
detectors
ion FFQs
2+3 m 2 m 2 m
very forward detection
(approximately to scale)
Ideal 4T solenoidwith 2 m tracker
Crossing angle
4-5 June 2010 EIC Detector Workshop at JLab 17
Analyzing magnet - dipole
• Analyzing magnet for high-momentum mesons and recoil baryons– Critical to ensure exclusivity and give access to full range in -t
• A 1-2 Tm dipole bypassed by the electron beam is very advantagous– No synchrotron radiation– Electron quads can be placed close to IP– Dipole field is not determined by electron energy– Positive particles are bent away from the electron beam– Dipole does not interfere with RICH and forward calorimeters
• Excellent hermeticityexclusive mesons
0.2 - 2.5°
recoil baryons
solenoid
electron FFQs3-5°
0°
analyzing magnet with detectors
ions
electrons
IP
detectors
ion FFQs
2+3 m 2 m 2 m
4 on
30
GeV
Q2 >
10
GeV
2
very forward detection
(approximately to scale)
4-5 June 2010 EIC Detector Workshop at JLab 18
Analyzing magnets - quadrupoles?
• By bending all charged particles, a dipole on the ion beam line– provides excellent resolution at small angles and does not interfere with optics– will bent away low-momentum particles scattered at small angles prior to quads– may limit very forward acceptance for neutrals within the quad aperture if field is too strong
solenoid
electron FFQs3-5°
0°
analyzing magnet with detectors
ions
electrons
IP
detectors
ion FFQs
2+3 m 2 m 2 m
very forward detection
(approximately to scale)
• Weak, large-aperture quads would not bend the ion beam and may impact forward detection less, but– a single quad, even if weak, will defocus the beam, reducing luminosity– a doublet will not affect the optics adversely, but makes tracking more complicated– a quad solution will provide less resolution, in particular at small angles– Would needs to be explored.
4-5 June 2010 19EIC Detector Workshop at JLab
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Figure-8 Collider Ring - Footprint
The ion beam has a 3-5° horizontal crossing angle
FF triplet : Q1 Q2 Q2
Very forward detection (< 0.5°)B
eam
size
at 6
0 G
eV
20-40 Tm dipole
Diffractive recoil protons for 4 on 50
• Diffractive processes• Spectator tagging• Coherent processes
• Quad gradient and aperture scale with distance
• Aperture angle depends only on Emax and quad length
4-5 June 2010 20EIC Detector Workshop at JLab
• The IP the IP is offset within the solenoid towars the electron endcap to provide more tracking space• Only active elements are shown. Detector can be “closed” magnetically
electrons
EM C
alor
imet
er
Had
ron
Cal
orim
eter
Muo
n D
etec
tor
EM C
alor
imet
er
Solenoid yoke + Hadronic Calorimeter
Solenoid yoke + Muon DetectorTOF
HTC
C
RIC
H
LTCC / RICH
Tracking
5 m
• TOF (5-10 cm)• DIRC (10 cm)
• Crossing angle: 3-5°• Magnet apertures for
small-angle ion and electron detection not shown
Central detector
EM Calorimeter
4-5 June 2010 EIC Detector Workshop at JLab 21
Identification of exclusive mesons at higher energies
• At higher ion energies a DIRC alone is no longer sufficient for π/K separation
4 on 30 GeV
s = 480 GeV2
5 on 50 GeV
s = 1000 GeV2
10 on 50 GeV
s = 2000 GeV2
• Need to cover meson momenta up to 7-9 GeV/c for operations at 60 GeV
Q2 >
10
GeV
2
• Two options– Supplement the DIRC with a gas Cerenkov (threshold or RICH)– Replace it with a dual radiator (aerogel / gas) RICH
4-5 June 2010 22EIC Detector Workshop at JLab
Central Detector
• 3-4 T solenoid with about 4 m diameter• Hadronic calorimeter and muon detector
integrated with the return yoke (c.f. CMS)
• TOF for low momenta– Precise timing also important for trigger
• p/K separation– DIRC or dual radiator (aerogel) RICH
• π/K separation options– DIRC + LTCC up to 9 GeV (higher if RICH)– dual radiator RICH up to ~8 GeV (?)
• e/π separation– C4F8O LTCC / RICH up to 3 / 5 GeV
– EC: Tungsten powder / scintillating fiber?
Solenoid Yoke, Hadron Calorimeter, MuonsSolenoid Yoke, Hadron Calorimeter, Muons
Particle IdentificationParticle Identification
• Vertex tracker (silicon pixel?)• Central tracker (DC, micropattern?)• Tracking planes (DC)
– Configuration to be optimized
Solenoid yoke + Hadronic Calorimeter
Solenoid yoke + Muon Detector
LTCC / RICH
Tracking
TrackingTracking
4-5 June 2010 23EIC Detector Workshop at JLab
Detector Endcaps
• Bore angle: ~45° (line-of-sight from IP)• High-Threshold Cerenkov• Time-of-Flight Detectors• Electromagnetic Calorimeter
• Bore angle: 30-40° (line-of-sight from IP)• Dual-radiator RICH (HERMES / LHCb ?)• Time-of-Flight Detectors• Electromagnetic Calorimeter• Hadronic Calorimeter• Muon detector (at least at small angles)
– Important for J/Ψ photoproduction (at low Q2)
TrackingTracking
Electron side (left)Electron side (left)
Ion side (right)Ion side (right)
• Forward / Backward– IP shifted to electron side (2+3 m)– Vertical planes in central tracker– Drift chambers on either side
EM C
alor
imet
erH
adro
n C
alor
imet
erM
uon
Det
ecto
r
EM C
alor
imet
er
TOF
HTC
C
RIC
HTracking
4-5 June 2010 EIC Detector Workshop at JLab 24
• Synchrotron radiation is not an issue for outgoing electrons– Can use dipole covering small scattering angles– Effect on electron emittance of strong dipole in high-β region?
• Common dipole requires additional steering to allow independently adjustable beam energies
• Endcap layout required for detailed design!
Low-Q2 tagging – very conceptual!
3-5°
0°
“tagger” detector(not to scale)
steering dipoles,compensatingsolenoid?
ion FFQs
electron FFQs
dipole
ions
electrons
endcap detectors
4-5 June 2010 25EIC Detector Workshop at JLab
• The exact endcap configuration will to a large extent depend on the readout for the DIRC
• The alternative configuration on the right provides easier access to the DIRC
EM C
alor
imet
erH
adro
n C
alor
imet
erM
uon
Det
ecto
r
Solenoid yoke + Hadronic Calorimeter
Solenoid yoke + Muon Detector
HTC
C
RIC
H
LTCC / RICHTracking
EM C
alor
imet
erH
adro
n C
alor
imet
erM
uon
Det
ecto
r
EM C
alor
imet
er
Solenoid yoke + Hadronic Calorimeter
Solenoid yoke + Muon Detector
HTC
C
RIC
H
RICH
Tracking
Electron endcap options
4-5 June 2010 EIC Detector Workshop at JLab 26
1. Central Detector1. Central Detector
2. Forward hadron detection2. Forward hadron detection
3. Low-Q3. Low-Q22 electron tagging electron tagging
• Particle ID (e/π/K/p)• Momentum resolution (tracker radius / layout)
Summary - main detector challenges
• Acceptance (3 stages needed)• Momentum resolution at intermediate angles (0.5-5°)
• Endcap design (DIRC readout?)• Common dipole for both beams?
4. Integration with accelerator4. Integration with accelerator