1. IR- and Detector Design Considerations
E.C. Aschenauer
EIC INT Program, Seattle Week 1

2. The Physics we want to study
What is the role of gluons and gluon self-interactions in nucleons and nuclei?
Observables in eA / ep:
diffractive events: rapidity gap events, elastic VM production, DVCS
structure functions F2A, FLA, F2cA, FLcA, F2p, FLp,………
What is the internal landscape of the nucleons?
What is the nature of the spin of the proton?
Observables in ep
inclusive, semi-inclusive Asymmetries
electroweak Asymmetries (g-Z interference, W+/-)
What is the three-dimensional spatial landscape of nucleons?
Observables in ep/eA
semi-inclusive single spin asymmetries (TMDs)
cross sections, SSA of exclusive VM, PS and DVCS (GPDs)
What governs the transition of quarks and gluons into pions and nucleons?
Observables in ep / eA
semi-inclusive c.s., ReA, azimuthal distributions, jets
E.C. Aschenauer
EIC INT Program, Seattle Week 1

3. Processes used to study the Physics
exclusive /diffractive
reactions
ep/A  e’p’/A’VM
semi-inclusive
reactions
ep/A e’pX
inclusive
reactions
ep/A  e’X
electro-weak
reactions
Close to 4p
acceptance
Excellent
electron
identification
Background
suppression
good jet
identification
PID:
to identify
Hadrons
Detect
outgoing
scattered
proton
excellent
absolute
and/or
relative
luminosity
Detect
very low Q2
electron
very precise
polarization
measurement
high demands on
momentum and/or
energy resolution
good vertex
resolution
E.C. Aschenauer
EIC INT Program, Seattle Week 1

4. Kinematics of scat. electron
Proton Energy
50 GeV GeV GeV
4 GeV GeV GeV
Electron Energy
scattered lepton
goes to smaller
angles as
√s increases
For any hadron beam energy
Q2>0.1GeV2
4GeV  >5o
10GeV  >2o
20GeV  >1o
E.C. Aschenauer
EIC INT Program, Seattle Week 1

5. Kinematics of semi-inclusive hadrons
no cuts:
4x50
4x100
4x250
cuts: Q2 > 0.1 GeV && y < 0.9 GeV
momentum (GeV)
hadrons go
more and more
forward with
increasing
asymmetry in
beam energies
E.C. Aschenauer
EIC INT Program, Seattle Week 1

6. Kinematics of elastic diffraction
no cuts:
4x100
4x50
4x250
cuts: Q2 > 0.1 GeV && y < 0.9 GeV
decay products of r & J/ψ
go more and more
forward with
increasing
asymmetry in
beam energies
E.C. Aschenauer
EIC INT Program, Seattle Week 1

7. Diffractive Physics: p’ kinematics
t=(p4-p2)2 = 2[(mpin.mpout)-(EinEout - pzinpzout)]
4 x 50 ?
Diffraction: p’
4 x 100
4 x 250
need “roman pots”
to detect the protons
and a ZDC for
neutrons
E.C. Aschenauer
EIC INT Program, Seattle Week 1

8. EIC INT Program, Seattle 2010 - Week 1
Additional Remarks
General Remarks
detector should have stable acceptance to enable efficient running at different energies (5 GeV x 50 GeV to 30 GeVx325 GeV)
Charm detection
structure functions
detecting lepton form decay in addition to scattered via displaced vertex should be enough
charm in fragmentation
need to reconstruct D0 meson completely to measure its z
 good PID
E.C. Aschenauer
EIC INT Program, Seattle Week 1

9. Measure gA(x) impact parameter dependent
Basic Idea:
Studying diffractive exclusive J/y production
at Q2~0
Ideal Probe:
large photo-production cross section
t can be derived from e,e’ and J/y 4-momentum
pt2 = t for elastic J/y
What are the requirement:
Momentum resolution
t resolution and range
what breakup particles need to
be detected?
n enough or p also needed?
A. Caldwell, H. Kowalski Phys.Rev.C81:025203,2010
E.C. Aschenauer
EIC INT Program, Seattle Week 1

10. How to measure coherent diffraction in e+A ?
Beam angular divergence limits smallest outgoing Qmin for p/A that can be measured
Can measure the nucleus if it is separated from the beam in Si (Roman Pot) “beamline” detectors
pTmin ~ pzAθmin
For beam energies = 100 GeV/n and
θmin = 0.1 mrad:
Large momentum kicks, much larger
than binding energy (~8 MeV)
Therefore, for large A, coherently diffractive nucleus cannot be separated from beamline without breaking up
species (A)
pTmin
(GeV/c)
d (2)
0.02
Si (28)
0.22
Cu (64)
0.51
In (115)
0.92
Au (197)
1.58
U (238)
1.90
E.C. Aschenauer
EIC INT Program, Seattle Week 1

11. How to measure coherent diffraction in e+A ?
Purity
Efficiency
rapidity
Rely on rapidity gap method
simulations look good
high eff. high purity
possible with gap alone
~1% contamination
~80% efficiency
depends critical on detector
hermeticity
improve further by veto on
breakup of nuclei (DIS)
Very critical
mandatory to detect nuclear
fragments from breakup
n: Zero-Degree calorimeter
p, A frag: Forward Spectrometer
E.C. Aschenauer
EIC INT Program, Seattle Week 1

12. Emerging Detector Concept
Forward / Backward
Spectrometers:
high acceptance -5 < h < 5 central detector
good PID and vertex resolution
tracking and calorimeter coverage the same  good momentum resolution
low material density  minimal multiple scattering and bremsstrahlung
forward electron and proton dipole spectrometers
E.C. Aschenauer
EIC INT Program, Seattle Week 1

13. First Model of eRHIC Detector
Si-Vertex
as Zeus
Central Tracker
as BaBar
Traditional
Drift-Chambers
better GEM-Tracker
Hadronic
Calorimeter
Dual-Radiator
RICH
as LHCb /
HERMES
EM-Calorimeter
PbGl
High Threshold
Cerenkov
fast trigger on e’
e/h separation
DIRC: not shown because of cut;
modeled following Babar
no hadronic calorimeter and m-ID jet
CALIC technology combines mID with HCAL
E.C. Aschenauer
EIC INT Program, Seattle Week 1

14. Technology choices and needed R&D
Some thoughts about technologies
LHC trackers have all to much radiation length
GEM trackers and ILC Si detectors would be much better
Forward calorimeters small moliere radius  PbWO4
especially important for hadron direction  DVCS
Preshower: g -p0 separation  Si-WO
Central calorimeter
needs to be compact with a pointing geometry
sampling calorimeter with accordion structure
Needed R&D
low mass trackers
compact calorimetry for inside solenoid
ion polarimetry  currently at best 5% systematic uncertainty at RHIC
Bjoerken sum rule measurement requires ~2%
E.C. Aschenauer
EIC INT Program, Seattle Week 1

15. EIC INT Program, Seattle 2010 - Week 1
IR-Design D5
eRHIC - Geometry high-lumi IR with β*=5 cm, l*=4.5 m and 10 mrad crossing angle Q5 Q4
Spin
rotator
325 GeV p
125 GeV/u ions
4 m
Dipole
0.44 m
6.33 mrad
3.67 mrad m
18.8 m
0.329 m
16.8 m m
10 mrad
30 GeV e- 10 20 30
60 m
90 m
© D.Trbojevic
E.C. Aschenauer
EIC INT Program, Seattle Week 1

16. A detector integrated into IR
space for
e-polarimetry
and luminosity
measurements
ZDC
FPD
FED
for ERL solution need not to measure electron polarization bunch by bunch
need still to integrate luminosity monitor
need still to integrate hadronic polarimeters, maybe at different IP
E.C. Aschenauer
EIC INT Program, Seattle Week 1

17. Can we detect DVCS-protons and Au break up p
track the protons through solenoid, quads and dipole with hector
beam angular spread 0.1mrad at IR
Quads +/- 5mrad acceptance
Proton-beam: p’z> 0.9pz
100 GeV: ptmax < 0.45 GeV  tmax < 0.2 GeV2
Detector: acceptance starts Θ > 50mrad
need more work to find a way to cover intermediate range
solution could be to do the same as for the electrons swap the
dipole and quads
proton track Dp=10%
proton track Dp=20%
proton track Dp=40%
Equivalent to fragmenting
protons from Au in Au optics
(197/79:1 ~2.5:1)
E.C. Aschenauer
EIC INT Program, Seattle Week 1

18. Jlab: Detector/IR cartoon
Slides Rolf Ent
Make use of a 100 mr crossing angle for ions!
detectors
(approximately to scale)
solenoid
ion dipole w/ detectors
ion FFQs IP
ions
0 mrad
electrons
100 mrad
electron FFQs
2+3 m
2 m
2 m
Central detector, more detection space in ion direction as particles have higher momenta
100 mr crossing angle
3.5 m distance IP – electron FFQs
 Easy to squeeze baby-size electron FFQs in here
Distance IP – electron FFQs = 3.5 m
Distance IP – ion FFQs = 7.0 m
E.C. Aschenauer
EIC INT Program, Seattle Week 1 18

19. Jlab: Where do particles go - mesons
Slides Rolf Ent
SIDIS p
1H(e,e’π+)n
4 on 60
11 on 60 { {
Need Particle ID for p > 4 GeV in central region
 DIRC won’t work, add threshold Cherenkov or RICH
Need Particle ID for well above 4 GeV in forward region (< 30o?)
 determines bore of solenoid
In general: Region of interest up to ~10 GeV/c mesons
Momentum ~ space needed for detection
E.C. Aschenauer
EIC INT Program, Seattle Week 1

20. Jlab: Overview of Central Detector Layout
Slides Rolf Ent
TOF
Solenoid yoke + Muon Detector
EM Calorimeter (30-50 cm)
Crystals, small area
Solenoid yoke + Hadronic Calorimeter
TOF (5-10 cm)
RICH
Muon Detector
Tracking
HTCC
RICH
EM Calorimeter
EM Calorimeter
Hadron Calorimeter
RICH ( cm)
C4F8O + Aerogel
Or DIRC (10 cm) + LTCC (60-80 cm)
C4F8O gas
π/K: GeV/c (threshold)
e/π: up to 2.7 GeV/c (LTCC)
K/p: up to 4 GeV/c (DIRC) 2m 3m 2m
IP is shown shifted left by 0.5 meter here, can be shifted
Determined by desired bore angle and forward tracking resolution
Flexibility of shifting IP also helps accelerator design at lower energies (gap/path length difference induced by change in crossing angle)
E.C. Aschenauer
EIC INT Program, Seattle Week 1

21. Jlab: Detector/IR cartoon
Slides Rolf Ent
Make use of a 100 mr crossing angle for ions!
detectors
(approximately to scale)
solenoid
ion FFQs
ion dipole w/ detectors IP
ions
0 mrad
electrons
100 mrad
electron FFQs
2+3 m
2 m
2 m
Detect particles with angles down to 0.5o
Need up to 2 Tm dipole bend, but not too much!
E.C. Aschenauer
EIC INT Program, Seattle Week 1 21

22. Jlab: Detector/IR cartoon
Slides Rolf Ent
Make use of a 100 mr crossing angle for ions!
detectors
(approximately to scale)
solenoid
ion dipole w/ detectors
ion FFQs IP
ions
0 mrad
electrons
100 mrad
electron FFQs
2+3 m
2 m
2 m °
4 on 30 GeV
Q2 > 10 GeV2
Downstream dipole on ion beam line ONLY has several advantages
No synchrotron radiation
Electron quads can be placed close to IP
Dipole field not determined by electron energy
Positive particles are bent away from the electron beam
Long recoil baryon flight path gives access to low -t
Dipole does not interfere with RICH and forward calorimeters
Excellent acceptance (hermeticity)
recoil baryons
exclusive mesons
E.C. Aschenauer
EIC INT Program, Seattle Week 1 22

23. EIC INT Program, Seattle 2010 - Week 1
and Summary
Quite some progress on integrating detector in machine design
Main features of detector design identified and implemented in design
BUT
need more feedback on requirements from physics groups
which hopefully comes with defining the physics program for an the INT
BNL: look into the possibilities to use existing detectors eSTAR, ePHENIX
eSTAR & ePHENIX look promising, but have some restrictions compared to a dedicated detector
E.C. Aschenauer
EIC INT Program, Seattle Week 1

24. EIC INT Program, Seattle 2010 - Week 1
BACKUP
E.C. Aschenauer
EIC INT Program, Seattle Week 1

25. Detector Requirements from Physics
Detector must be multi-purpose
Need the same detector for inclusive (ep -> e’X), semi-inclusive (ep -> e’hadron(s)X), exclusive (ep -> e’pp) reactions and eA interactions
Able to run for different energies (and ep/A kinematics) to
reduce systematic errors
Ability to tag the struck nucleus in exclusive and diffractive eA reactions
Needs to have large acceptance
Cover both mid- and forward-rapidity
particle detection to very low scattering angle; around 1o in e and p/A direction
particle identification is crucial
e, p, K, p, n over wide momentum range and scattering angle
excellent secondary vertex resolution (charm)
small systematic uncertainty for e,p-beam polarization and luminosity measurement
E.C. Aschenauer
EIC INT Program, Seattle Week 1

26. eRHIC – Geometry high-lumi IR
eRHIC IR1
p /A e
Energy (max), GeV
325/130 20
Number of bunches
166
74 nsec
Bunch intensity (u) , 1011
2.0
0.24
Bunch charge, nC 32 4
Beam current, mA
420 50
Normalized emittance, 1e-6 m, 95% for p / rms for e
1.2 25
Polarization, % 70 80
rms bunch length, cm
4.9
0.2
β*, cm 5
Luminosity, cm-2s-1
1.46 x 1034
(including hour-glass effect h=0.851)
1.6 m 1 3 2 4 5 6
0.85 m 7
10 mrad
5.4 cm
8.4 cm
10.4 cm
1 m
© D.Trbojevic m
Two designs of the IR exist for both low luminosity (~ 3x1033) and high luminosity (~ 2x1034) depends on distance IR to focusing quads
By using a crossing angle (and crab cavities), one can have energy-independent geometries for the IRs and no synchrotron radiation in the detectors
Big advantage in detecting particles at low angle
can go as low as 0.75o at hadron side  |h| < 5.5 Beam-p: y ~ 6.2
Luminosity for 30 GeV e-beam operation will be at 20% level
E.C. Aschenauer
EIC INT Program, Seattle Week 1

27. EIC INT Program, Seattle 2010 - Week 1
RHIC
Tracking: TPC
Particle ID: TOF
Electromagnetic Calorimetry:
BEMC+EEMC+FMS
(-1 ≤ η ≤ 4)
Upgrades:
Muon Tracking Detector
HLT
Heavy Flavor Tracker (2013)
Forward Gem Tracker
(2011)
Full azimuthal particle identification
over a broad range in pseudorapidity
E.C. Aschenauer
EIC INT Program, Seattle Week 1

28. EIC INT Program, Seattle 2010 - Week 1
Kinematics at 4+100
Scattered electron
Scattered jet
4x100 open kinematics: scatters the electron and jet to mid-rapidity
Forward region (FMS): Electron either Q2 < 1 GeV, or very high x and Q2
Jet either very soft or very hard
Note: current thinking has hadron in the blue beam: optimized for high x and Q2
E.C. Aschenauer
EIC INT Program, Seattle Week 1

29. Current PHENIX Detector at RHIC
MPC < | h | < 3.9
2.5o < Q < 5.2o
Muon Arms < | h | < 2.4
South: o < Q < 37o
North: o < Q < 37o
Central Arms | h | < 0.35
60o < Q < 110o
electrons will not make it
to the south muon arm
to much material
would like to have hadrons in blue beam and leptons in yellow beam direction e-
E.C. Aschenauer
EIC INT Program, Seattle Week 1

30. What will the current PheniX see
pe: 0-1 GeV
pe: 1-2 GeV
pe: 2-3 GeV
pe: 3-4 GeV
4x100
Current PheniX detector
not really useable for
DIS
acceptance not matched to DIS kinematics
BUT ….
4x100
4x100
E.C. Aschenauer
EIC INT Program, Seattle Week 1

31. The new PheniX Spectrometer
Coverage in |h| =< 4 (2o < q < 30o) 0.1 < Q2 < 100 (5o – 175o)
need an open geometry detector
planes for next decadal plan
replace current central detector with a new one covering |h| =< 1
replace South muon arm by a endcap spectrometer
North Muon Arm
145cm
HCAL
the new PheniX detector can make
Summary:
important measurements
Lets integrate it fully into the design
in ep/eA
and the next decadal plan
80cm
HCAL
EMCAL
EMCAL
68cm
2T Solenoid
RICH
Preshower
60cm
Silicon Tracker
VTX + 1 layer IP
Silicon Tracker
FVTX
1.2 < h < 2.7
8o < q < 37o 2m
17.4 cm dy
E.C. Aschenauer
EIC INT Program, Seattle Week 1