EIC Detectors
Tanja Horn
INT10-3 “Science Case for an EIC”,
Institute for Nuclear Theory, UW, Seattle
Tanja
Horn,
EICCUA
Detectors,
INT10-3
Tanja
Horn,
Colloquium
16 November 2010
1
Science of an EIC: Explore and Understand QCD
•
Map the spin and 3D quark-gluon structure of nucleons
Image the 3D spatial distributions of gluons and sea quarks through exclusive J/Ψ, γ (DVCS) and
meson production
̶
Measure ΔG, and the polarization of the sea quarks through SIDIS, g1, and open charm production
̶
Establish the orbital motion of quarks and gluons through transverse momentum dependent
observables in SIDIS and jet production
•
̶
Discover collective effects of gluons in nuclei
•
̶
Discover signatures of dynamics of strong color fields in nuclei at high energies in
and eA->e’hadronsX
eA->e’X(or A)
̶
Measure fundamental gluon/quark radii of nuclei through coherent scattering g* + A  J/Y + A
̶
Explore the nuclear modification of the nucleon's basic gluonic momentum and spatial structure
through e + A  e‘ + X and e + A  e' + cc + X
Understand the emergence of hadronic matter from quarks and gluons
−
Explore the interaction of color charges with matter (energy loss, flavor dependence, color
transparency) through hadronization in nuclei in e + A  e' + hadrons + X
−
Understand the conversion of quarks and gluons to hadrons through fragmentation of correlated
quarks and gluons and breakup in e + p  e' + hadron + hadron + X
Tanja Horn, EIC Detectors, INT10-3
2
To cover the physics we need…
ss
Range in y
Q2 ~ xys
• For large or small y, uncertainties in the
kinematic variables become large
• Detecting only the electron ymax / ymin ~ 10
• Also detecting all hadrons ymax / ymin ~ 100
– Requires hermetic detector (no holes)
C. Weiss
Range in s
C.Weiss
Weiss
C.
[Weiss 09]
• Accelerator considerations limit smin
– Depends on smax (dynamic range)
Range of kinematics
•
At fixed s, changing the ratio Ee / Eion can for
some reactions improve resolution, pid, and
acceptance
radiative
gluons/sea
non-pert. sea
quarks/gluons
valence
quarks/gluons
– Luminosity may be lower than shown in profile
Tanja Horn, EIC Detectors, INT10-3
3
Detector Requirements
1. To a large extent driven by exclusive physics
•
•
•
•
•
•
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)
2. But not only ...
• Very forward detection (spectator tagging, diffractive, coherent
nuclear, etc)
• Vertex resolution (charm)
• Hadronic calorimetry (jet reconstruction)
Tanja Horn, EIC Detectors, INT10-3
4
Where do particles go - general
e
p or A
Several processes in e-p:
1)
“DIS” (electron-quark scattering)
2)
“Semi-Inclusive DIS (SIDIS)”
3)
“Deep Exclusive Scattering (DES)” e + p  e’ + photon/meson + baryon
4)
Diffractive Scattering
e + p  e’ + p + X
5)
Target fragmentation
e + p  e’ + many mesons + baryons
Token example:
1H(e,e’π+)n
e + p  e’ + X
e + p  e’ + meson + X
Even more processes in e-A:
1)
“DIS”
e + A  e’ + X
2)
“SIDIS”
e + A  e’ + meson + X
3)
“Coherent DES”
e + A  e’ + photon/meson + nucleus
4)
Diffractive Scattering
e + A  e’ + A + X
5)
Target fragmentation
e + A  e’ + many mesons + baryons
6)
Evaporation processes
e + A  e’ + A’ + neutrons
In general, e-p and even more e-A colliders have a large fraction of their science related to the detection of what
happens to the ion beams. The struck quark remnants can be guided to go to the central detector region with Q2 cuts,
but the spectator quark or struck nucleus remnants will go in the forward (ion) direction.
[Ent 10]
Tanja Horn, EIC Detectors, INT10-3
5
Scattered Electron Kinematics
low-Q2 electrons
high-Q2 electrons in
central barrel:
1-2 < p < 4 GeV
10 on 60
in
Momentum (GeV/c)
Momentum (GeV/c)
electron endcap
Electron Scattering Angle (deg)
Electron Scattering Angle (deg)
• Modest (up to ~6 GeV) electron energies in central & forward-ion direction.
• Electrons create showers  electron detectors are typically compact.
•Larger energies (up to Ee) in the forward-electron direction: low-Q2 events.
[Horn 08+]
Tanja Horn, EIC Detectors, INT10-3
6
Diffractive and SIDIS (TMDs)
[W. Foreman 09]
diffractive
4 on 50 GeV
4 on 250 GeV
• Both processes produce
high-momentum
mesons at small angles
DIS
• Small angle detection
important for
understanding target
fragmentation
10°
5°
Tanja Horn, EIC Detectors, INT10-3
7
Exclusive light meson kinematics
mesons
scattered electrons
very high
momenta
recoil baryons
4 on 250 GeV
0.2° - 0.45°
PID challenging
4 on 30 GeV
electrons in
central barrel,
but p different
0.2° - 2.5°
t/t ~ t/Ep
Θ~√t/Ep
ep → e'π+n
Tanja Horn, EIC Detectors, INT10-3
8
Horn 08+
Where do particles go - baryons
t ~ Ep2Q2  Angle recoil baryons = t½/Ep
Ep = 12 GeV
Ep = 30 GeV
Ep = 60 GeV
DQ = 1.3
DQ = 5
[Horn 08+]
Nuclear Science: Map t between tmin and 1 (2?) GeV
 Must cover between 1 and 5 degrees
 Should cover between 0.5 and 5 degrees
t resolution
~ Q ~ 1 mr
 Like to cover between 0.2 and 7 degrees
Tanja Horn, EIC Detectors, INT10-3
9
DES at higher electron energies
5 on 50
10 on 50
Momentum (GeV/c)
4 on 30
Lab Scattering angle (deg)
Lab Scattering angle (deg)
Lab Scattering angle (deg)
•
Need particle ID for p>4 GeV/c in central region
•
A DIRC is not sufficient for π/K separation already at relatively modest energies
•
Most important for exclusive reactions, but also for SIDIS, etc.
•
Two options
̶
Supplement the DIRC with a C4F8O gas Cherenkov (threshold or RICH)
̶
Replace it with a dual radiator (aerogel/gas) RICH
[Horn 08+]
Tanja Horn, EIC Detectors, INT10-3
10
MEIC interaction region and central
detector layout
low-Q2
electron detection
central detector with endcaps
large aperture
electron quads
ultra forward
hadron detection
small angle
hadron detection
dipole
ion quads
dipole
IP
dipole
small diameter
electron quads
3° beam (crab) crossing angle
Solenoid yoke + Muon Detector
•
EM Calorimeter
Hadron Calorimeter
Muon Detector
Tracking
RICH
Cerenkov
HTCC
EM Calorimeter
Solenoid yoke + Hadronic Calorimeter
Apertures for small-angle
ion and electron
detection not shown
TOF (+ DIRC ?)
5 m solenoid
11
Tanja Horn, EIC Detectors, INT10-3
Forward Ion Detection
(“full-acceptance” detector)
Three-stage strategy using 50 mrad crossing angle
solenoid
(approximately to scale)
detectors
ion dipole w/ detectors
0 mrad
IP
50 mrad
electrons
electron FFQs
2+3 m
Central detector, more
detection space in ion
direction as particles
have higher momenta.
2m
2m
Detect particles with angles down to
0.5° (10 mrad) before ion FFQs.
Need 2 Tm dipole (for 100 GeV proton
beams) in addition to central solenoid.
Detect particles with
angles below 0.5°
using 20 Tm dipole
beyond ion FFQs.
Distance IP – ion FFQs = 7 m
(Driven by push to 0.5 degrees detection before ion FFQs)
Tanja Horn, EIC Detectors, INT10-3
12
Detector Endcaps
Electron side (left)
• Bore angle: ~45° (line-of-sight from IP)
TOF
• Electromagnetic Calorimeter (e/π)
Tracking
EM Calorimeter
Hadron Calorimeter
Muon Detector
Hadrons, event reconstruction, trigger
RICH
̶
EM Calorimeter
• Time-of-Flight Detectors
HTCC
• High-Threshold Cerenkov (e/π)
Ion side (right)
• Bore angle: 30-40° (line-of-sight from IP)
• Ring-Imaging Cerenkov (RICH)
• Time-of-Flight Detectors (event recon., trigger)
• Electromagnetic Calorimeter
̶
Pre-shower for γ/π° -> γγ
small opening angle at high p)
(very
• Hadronic Calorimeter (jets)
Space constraints
• Electron side has a lot of space
• Ion side limited by distance to
FFQ quads (7 m)
• Muon detector (J/Ψ production at low Q2)
Tanja Horn, Introduction to EIC/detector concept,
Tanja
Horn,
EIC Detectors,
INT10-3
Exclusive
Reactions
Workshop
2010
13
Central Detector
Solenoid Yoke, Hadron Calorimeter, Muons
•
3-4 T solenoid with about 4 m diameter
•
Hadronic calorimeter and muon detector
integrated with the return yoke (c.f. CMS)
Solenoid yoke + Muon Detector
Solenoid yoke + Hadronic Calorimeter
LTCC / RICH
Tracking
Particle Identification
• TOF for low momenta
• π/K separation options
– DIRC up to 4 GeV
– DIRC + LTCC (or dual radiator RICH): up to 9 GeV
• p/K separation
̶
Tracking
• Low-mass vertex tracker
DIRC up to 7 GeV
• GEM-based central tracker
• e/π separation
– C4F8O LTCC up to 3 GeV
• Conical endcap trackers
Tanja Horn, Introduction to EIC/detector
Tanja
Horn, EIC
Detectors,
INT10-3
concept,
Exclusive
Reactions
Workshop
2010
14
Resolution dp/p in solenoid
175°
particle momentum = 5 GeV/c
4 T ideal solenoid field
cylindrical tracker with 1.25 m radius (R1)
Δp/p ~ σp / BR2
•
position resolution σ~ 100 microns
–
•
Tracker (not magnet!) radius R is important
at central rapidities
R2
R1
–
Crossing angle
Goal: dp/p ~ 1% @ 10 GeV/c
CLAS DCs designed for 150 microns
Conical trackers improve resolution at
endcap corners by (R2/R1)2 ~ 4 (not shown)
•
Only solenoid field B (not R)
matters at very forward rapidities
•
A 2 Tm dipole covering 3-5°
eliminates divergence at small angles
•
A 3° beam crossing angle moves
the region of poor resolution away
from the ion beam center line.
– 2D problem!
Tanja Horn, EIC Detectors, INT10-3
15
Use Crab Crossing for Very-Forward Detection
(Reminder: MEIC/ELIC scheme uses 50 mr crab crossing)
Present thinking: ion beam has 50 mr horizontal crossing angle
Renders good advantages for very-forward particle detection
Figure-8 Collider Ring - Footprint
10000
ions
ions
8000
6000
4000
2000
x [cm]
-20000
0
-15000
-10000
-5000
-2000
0
5000
10000
15000
20000
-4000
-6000
-8000
-10000
[Zhang09+]
z [cm]
20 Tm dipole @ ~20 m from IP
Tanja Horn, EIC Detectors, INT10-3
16
MEIC Interaction Region – forward tagging
Very forward ion tagging
Thu Jul 15 22:52:10 2010
OptiM - MAIN: - C:\Working\ELIC\MEIC\Optics\Ion Ring_900\Arc_Straight_IR_Str_90_in_2.o
5
2600
[Bogacz 10]
DISP_X&Y[m]
BETA_X&Y[m]
ions
Arc end
20 Tm
analyzing
dipole
IP
0
-5
Chromaticity Compensation Block
BETA_Y
DISP_X
DISP_Y
348.93
650
650
OptiM - MAIN: - C:\Working\ELIC\MEIC\Optics\5GeV Electe. Ring\Spin_rotator_match_7_IR.
Thu Jul 15 22:13:10 2010
OptiM - MAIN: - C:\Working\ELIC\MEIC\Optics\Disp_Fi
1
BETA_X
Thu Jul 15 22:14:56 2010
1
239
0
BETA_X
BETA_Y
DISP_X
DISP_X&Y[m]
DISP_X&Y[m]
-1
269
73.5928
DISP_Y
-1
BETA_X&Y[m]
0
0
BETA_X&Y[m]
electrons
BETA_X
8 m drift space after low-Q2
tagger dipole
Arc end
Spin Rotator
BETA_Y
IR
DISP_X
DISP_Y326
Chromaticity
Compensation
Block
17
Tanja Horn, EIC Detectors, INT10-3
Detector/IR – Forward & Very Forward
• Ion Final Focusing Quads (FFQs) at 7 meter, allowing ion detection
down to 0.5o before the FFQs (BSC area only 0.2o)
• Use large-aperture (10 cm radius) FFQs to detect particles
between 0.3 and 0.5o (or so) in few meters after ion FFQ triplet
sx-y @ 12 meters from IP = 2 mm
12 s beam-stay-clear  2.5 cm
0.3o (0.5o) after 12 meter is 6 (10) cm
 enough space for Roman Pots &
small-angle calorimeters
• Large dipole bend @ 20 meter from IP (to correct the 50 mr ion horizontal
crossing angle) allows for very-small angle detection (< 0.3o)
sx-y @ 20 meters from IP = 0.2 mm
10 s beam-stay-clear  2 mm
2 mm at 20 meter is only 0.1 mr…
D(bend) of 29.9 and 30 GeV spectators is 0.7 mr = 2.7 mm @ 4 m
Situation for zero-angle neutron detection very similar as at RHIC!
[Slide from R. Ent 10]
Tanja Horn, EIC Detectors, INT10-3
18
Backgrounds and detector placement
Synchrotron radiation
•
From arc where electrons exit and magnets on straight section
Random hadronic background
•
Dominated by interaction of beam ions with residual gas in beam pipe between arc and IP
•
Comparison of MEIC (at s = 4,000) and HERA (at s = 100,000)
−
−
−
−
Distance from ion exit arc to detector: 50 m / 120 m = 0.4
Average hadron multiplicity: (4000 / 100000)1/4 = 0.4
p-p cross section (fixed target): σ(90 GeV) / σ(920 GeV) = 0.7
At the same ion current and vacuum, MEIC background should be about 10% of HERA
o Can run higher ion currents (0.1 A at HERA)
o Good vacuum is easier to maintain in a shorter section of the ring
• Backgrounds do not seem to be a major problem for the MEIC
− Placing high-luminosity detectors closer to ion exit arc helps with both background types
− Signal-to-background will be considerably better at the MEIC than HERA
o MEIC luminosity is more than 100 times higher (depending on kinematics)
Tanja Horn, EIC Detectors, INT10-3
19
JLab and BNL central detector layouts similar
JLab
[Nadel-Turonski talk week 5]
BNL
[Aschenauer talk week 1&8]
Solenoid yoke + Muon Detector
EM Calorimeter
Hadron Calorimeter
Muon Detector
Tracking
RICH
Cerenkov
HTCC
EM Calorimeter
Solenoid yoke + Hadronic Calorimeter
5 m solenoid
Minor differences
•
•
•
•
•
JLab layout has conical rather than cylindrical forward / backward trackers (with line-of-sight from IP)
JLab detector does not have the forward RICH inside the solenoid magnet
JLab detector reserves space for DIRC readout (but details need to be worked out!)
JLab detector allocates space for Cerenkov (LTCC) in central barrel for high-momentum PID
JLab interaction region has a larger ion beam crossing angle 50-60 mrad vs 10 mrad
20
Tanja Horn, EIC Detectors, INT10-3
eRHIC Detector Concept
Forward / Backward
Spectrometers:
[Aschenauer talk week 1&8]
 central detector acceptance: very high coverage -5 < h < 5
 Tracker
same
2m and ECal coverage the4m

crossing angle: 10 mrad; Dy = 2cm and Dx = 2/4cm (electron/proton direction)
 Dipoles needed to have good forward momentum resolution and acceptance
 DIRC, RICH hadron identification  p, K, p
 low radiation length extremely critical  low lepton energies
 precise vertex reconstruction (< 10 mm)  separate Beauty and Charmed Meson
Tanja Horn, EIC Detectors, INT10-3
21
IR-Design-Version-I
[Aschenauer talk week 1]
eRHIC - Geometry high-lumi IR with β*=5 cm, l*=4.5 m
and 10 mrad crossing angle
Assume 50% operations efficiency
10
20
0.329 m
0.188036 m
0.44 m
 4fb-1 / week
30 GeV e-
30
60 m
90 m
© D.Trbojevic
Tanja Horn, EIC Detectors, INT10-3
22
IP configuration for eRHIC –
4.5
cm
Version-II
p /2.5
Estimated b ≈ 8 cm
neutrons
[Aschenauer talk week 8]
*
c
11.2 cm
q=10 mrad
e IP
2
4
6
8
10
12
14
Dipole:
Quad Gradient:
2.5 m, 6 T
200 T/m
16
q=18 mrad
Tanja Horn, EIC Detectors, INT10-3
23
IP configuration for eRHIC –
Version-II
[Aschenauer talk week 8]
5.75 cm
10
17.65 m
20
0.44843 m
0.39065 m
0.333 m
D5
30
60.0559 m
90.08703 m
Tanja Horn, EIC Detectors, INT10-3
24
Summary
•
JLab and BNL detector concepts generally similar
•
Goal: hermetic detector with high resolution over full acceptance
•
Emphasis on small-angle coverage
̶
Three stage approach for forward hadron detection
•
Detector is well suited for a wide range of experiments
•
Integration with accelerator important
Tanja Horn, EIC@JLab - taking nucleon structure
Tanja Horn, EIC Detectors, INT10-3
beyond the valence region, INT09-43W
25
Backup material
Tanja Horn, EIC@JLab - taking nucleon structure
Tanja Horn, EIC Detectors, INT10-3
beyond the valence region, INT09-43W
26
Scattered Electron Kinematics
low-Q2 electrons
4 on 60
Momentum (GeV/c)
Momentum (GeV/c)
electron endcap
in
high-Q2 electrons
in central barrel:
1-2 < p < 4 GeV
• Modest (up to ~6 GeV) electron energies in central & forward-ion direction.
• Electrons create showers  electron detectors are typically compact.
• Larger energies (up to Ee) in the forward-electron direction: low-Q2 events.
• Requirements on the electron side are dominated by near-photon physics:
electrons need to be peeled away from beam by tagger magnet(s).
Tanja Horn, EIC Detectors, INT10-3
27
Kinematic Coverage
x ~ Q2/ys
Q2 (GeV2)
Q2 (GeV2)
[Nadel-Turonski 09]
mEIC at JLab, 11 on 60
GeV
JLab 12 GeV
H1
ZEUS
LHeC Experiment
New physics on
scales ~10-19
High precision
partons in LHC
plateau
s (CM energy)
High
Density
Matter
HERA, y=0.004
Large x
partons
Nuclear
Structure &
Low x Parton
Dynamics
mEIC 3 on 20, y=0.004
x
x
A medium-energy EIC is complementary to the LHeC
•
Overlaps with HERA and the LHeC
•
Overlaps (or close to overlap) with JLab 12 GeV
•
Gives an order of magnitude higher reach in s than COMPASS and a much higher luminosity
Tanja Horn, EIC Detectors, INT10-3
28
Detector/IR in pocket formulas
• Luminosity ~ 1/b*
• bmax ~ 2 km = l2/b*
(l = distance IP to 1st quad)
l = 7 m, b* = 20 mm  bmax = 2.5 km
Example:
• IP divergence angle ~ 1/sqrt(b*)
Example:
l = 7 m, b* = 20 mm  angle ~ 0.3 mr
Example: 12 s beam-stay-clear area
•
 12 x 0.3 mr = 3.6 mr ~ 0.2o
FFQ gradient ~ Ep,max /sqrt(b*) (for fixed b , magnet length)
Example: 6.8 kG/cm for Q3 @ 12 m @ 60 GeV
max
 7 T field for 10 cm (~0.5o) aperture
Making
b* too small complicates small-angle (~0.5o) detection before ion Final Focusing Quads, and would require too
high a peak field for these quads given the large apertures (up to ~0.5 o). b*
= 1-2 cm and Ep = 20-60+ GeV
ballpark right!
Tanja Horn, EIC Detectors, INT10-3
29