Overview ofeRHIC detector design studies

1
Overview ofeRHIC detector design studies
2
Outline

• Kinematics reconstruction

• Structure Function Measurement

• eRHIC - Detector requirements

• QCD basics

• eRHIC - Detector design aspects

• DIS - Kinematics and Structure Functions

• Concluding remarks

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
3

DIS - Kinematics and Structure Functions

• Quantitative description of electron-proton
  scattering

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
4

DIS - Kinematics and Structure Functions

• Rutherford cross-section

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
5

DIS - Kinematics and Structure Functions

• Quantify the nucleus structure Form factors
  (Elastic scattering)

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
6

DIS - Kinematics and Structure Functions

• Quantify the nucleon structure Form factors
  (Elastic scattering)

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
7

DIS - Kinematics and Structure Functions

• Quantify proton structure Structure functions
  (Inelastic case)

• Scattering of electron (Spin 1/2) on proton (Spin
  1/2)

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
8

DIS - Kinematics and Structure Functions

• Structure function measurement Formalism
• In terms of laboratory variables
• Formulate this now in relativistic invariant
  quantities
• Instead of W1 and W2, use F1 and F2

Longitudinal structure function FL
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
9

QCD basics

• Fundamental QCD ingredients

• Evolution
• Beyond Quark-Parton model, Parton densities
  become functions of Q2
• Predict Q2 dependence of parton distribution
  functions (evolution equations)

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
10

QCD basics

• Asymptotic freedom

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
11

QCD basics

• Factorization

• Three steps
• Partons (quarks/gluons) in initial state Long
  distance (non-perturbative QCD domain)
• ? Parton (quarks/gluons) distribution functions
• Hard interaction Small distances (high energies)
  (perturbative QCD domain)
• ? Cross-section prediction
• Quarks in final state Long distance
  (non-perturbative QCD domain)
• ? Quarks fragment into observable hadrons
  described by fragmentation functions

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
12

QCD basics

• Evolution (1)
• The presence of QCD related diagrams leads to a
  modification of F2

Logarithmic violation of scaling
Parton model
Gluon radiation
Splitting function
Quark densities depend on x and Q2
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
13

QCD basics

• Evolution (2)
• Consider the change of the quark density ?q(x,Q2)
  over an interval of ?logQ2
• General including other types of splitting
  functions

Singlet distribution
Probability of finding a parton of type i with
momentum fraction x which originated from parton
j having momentum fraction y!
Gluon distribution
DGLAP evolution equations G. Altarelli and G.
Parisi, Nucl. Phys. B 126 (1977) 298 V. Gribov
and L.N. Lipatov, Soc. J. Nucl. Phys. 15 (1972)
438 L.N. Lipatov, Soc. J. Nucl. Phys. 20 (1975)
96 Y.L. Dokshitzer, Soc. Phys. JETP 46 (1977)
641.
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
14

Structure Function Measurement

• Structure function measurement Kinematic
  coverage and measurement

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
15

Structure Function Measurement

• Structure function measurement Picture of the
  Proton

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
16

Structure Function Measurement

• Evolution

At higher and higher resolutions, the quarks emit
gluons, which also emit gluons, which emit
quarks, which!
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
17

Structure Function Measurement

• Structure function measurement Q2 and x
  dependence

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
18

Structure Function Measurement

• Extracting parton distribution functions
• Determine F2QCD in terms of parton distribution
  functions
• Evolve F2QCD through parton distribution
  functions based on evolution equations
• Minimize ?2 in terms of F2QCD and F2data by
  adjusting parameters in xfi(x,Q2)
• Net result QCD prediction for xfi(x,Q2) and
  therefore F2(x,Q2)
• Various global pdf analyses
• GRV
• CTEQ
• MRST
• ZEUS/H1

i valence (u,d), sea (s) and gluon (g)
Low x ?i
High x ?i
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
19

Structure Function Measurement

• Extrapolation of ZEUS NLO DGLAP fit towards low
  Q2

FL negative at low Q2 and low x!
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
20
Structure Function Measurement

• Reconstruction of F2

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
21
Structure Function Measurement

• Reconstruction of F2

Requires unfolding!
Correct for FL to get F2!
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
22

Kinematics reconstruction

• Reconstruction of event kinematics

• Electron method scattered electron

• Jacquet-Blondel method hadronic final state

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
23

Kinematics reconstruction

• Event kinematics (10GeV electron on 250GeV
  proton)

Lines of constant electron angle (?e)
Lines of constant electron energy (Ee)
Lines of constant hadron angle (?)
Lines of constant hadron energy (F)
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
24

Kinematics reconstruction

• Event topology (10GeV electron on 250GeV proton)

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
25

Kinematics reconstruction

• Event kinematics (5GeV electron on 50GeV proton)

Lines of constant electron energy (Ee)
Lines of constant electron angle (?e)
Lines of constant hadron energy (F)
Lines of constant hadron angle (?)
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
26

Kinematics reconstruction

• Event topology (5GeV electron on 50GeV proton)

• High-x-high Q2
• Electron predominantly in barrel/forward
  direction (High energy) and current jet in
  forward direction (High energy)

• Low-x-low Q2 Electron and current jet (low
  energy) predominantly in rear direction
• High-x-low Q2
• Electron in rear and current jet (High energy) in
  forward direction

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
27

Kinematics reconstruction

• Resolution of event kinematics

• Electron method scattered electron

• Jacquet-Blondel method hadronic final state

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
28
eRHIC - Detector requirements

• Polarized ep physics
• Precision measurement of gp1 over wide range in
  Q2
• Extraction of gluon polarization through DGLAP
  NLO analysis
• Extraction of strong coupling constant
• Precision measurement of gn1 (neutron) (Polarized
  3He)
• Photoproduction measurements
• Electroweak structure function g5 measurements
• Flavor separation through semi-inclusive DIS
• Target and current fragmentation studies
• Transversity measurements

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
29

eRHIC - Detector requirements

• Unpolarized ep/eA physics
• Precision measurement of F2 at low x Transition
  from hadronic to partonic behavior
• Precision measurement of the longitudinal
  structure function FL
• Precision measurement of F2 at high x
• Measurement of diffractive and exclusive
  reactions
• DVCS
• Precision measurement of eA scattering

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
30

eRHIC - Detector requirements

• Detector specifications (1)
• Tracking over wide acceptance range operating in
  high-rate environment - Contribute to
  reconstruction of event kinematics besides
  calorimetry in particular at very small energies
• Calorimetry over wide acceptance range (e/h
  separation critical) Transverse and longitudinal
  segmentation (Track-calorimeter cluster matching
  essential)
• Specialized detector systems
• Zero-degree photon detector (Control radiative
  corrections and luminosity measurement)
• Tagging of forward particles (Diffraction and
  nuclear fragments) such as
• Proton remnant tagger
• Zer0-degree neutron detector
• Particle ID systems (K/p separation), secondary
  vertex reconstruction and muon system (J/Psi)

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
31

eRHIC - Detector requirements

• Detector specifications (2)
• High-rate rate requirement
• Background rejection Timing requirements e.g.
  calorimetry timing essential to reject beam
  related background
• Trigger Multi-level trigger system involving
  calorimetry and fast tracking information to
  enhance data sample for rare processes over
  inclusive ep/eA and photoproduction

ATLAS
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
32

eRHIC - Detector design aspects

• General considerations Detector aspects
• Measure precisely scattered electron over large
  polar angle region (Kinematics of DIS reaction)
• Tag electrons under small angles (Study of
  transition region DIS and photoproduction)
• Measure hadronic final state (Kinematics, jet
  studies, flavor tagging, fragmentation studies,
  particle ID)
• Missing ET for events with neutrinos in the final
  state (W decays) (Hermetic detector)
• Zero-degree photon detector Control radiative
  corrections and luminosity measurement (ep/eA
  Bremsstrahlung)
• Tagging of forward particles (Diffraction and
  nuclear fragments) such as
• Proton remnant tagger
• Zero degree neutron detector
• Challenge to incorporate above in one detector
  Focus on two specific detector concepts for now!

Constrain on machine layout!
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
33
eRHIC - Detector design aspects

• General considerations
• Design 1 Forward physics (unpolarized eA MPI
  Munich group)
• Specialized detector system to enhance forward
  acceptance of scattered electrons and hadronic
  final state
• Main concept Long inner dipole field (7m)
• Required machine element-free region approx. 5m
• Design 2 General purpose (unpolarized/polarized
  ELECTRon-A)
• Compact central detector (Solenoidal magnetic
  field) with specialized forward/rear tagging
  detectors/spectrometers to extend central
  detector acceptance
• Required machine element-free region approx. 3m
• Detector sub-systems in both design concepts
• Zero-degree photon detector (Control radiative
  corrections and luminosity measurement)
• Tagging of forward particles (Diffraction and
  nuclear fragments) such as
• Proton remnant tagger / proton spectrometer
• Zer0-degree neutron detector

A
e
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
34
eRHIC - Detector design aspects

• Design 1 Forward physics (unpolarized eA
  MPI-Munich group) (1)
• Detector concept
• Compact detector with tracking and central EM
  calorimetry inside a magnetic dipole field and
  calorimetric end-walls outside
• Bend forward charged particles into detector
  volume
• Extend rapidity compared to existing detectors
• Tracking focuses on forward and backward tracks
• No tracking in central region

I. Abt, A. Caldwell, X.
Liu, J. Sutiak, MPP-2004-90, hep-ex
0407053
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
35
eRHIC - Detector design aspects

• Design 1 Forward physics (unpolarized eA
  MPI-Munich group) (2)

I. Abt, A. Caldwell, X.
Liu, J. Sutiak, MPP-2004-90, hep-ex
0407053

• Tracking system
• High-precision tracking with ?pT/pT 2
• Angular coverage down to ? 6 over the full
  energy range
• Concept 14 Si-strip tracking stations
  (40 X 40 cm)
• Assumed hit resolution 20µm
• Momentum resolution from simulations Few percent!

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
36
eRHIC - Detector design aspects

• Design 1 Forward physics (unpolarized eA
  MPI-Munich group) (3)

I. Abt, A. Caldwell, X.
Liu, J. Sutiak, MPP-2004-90, hep-ex
0407053

• Calorimeter system
• Compact EM calorimeter systems Si-Tungsten
• Forward hadron calorimeter Design follows
  existing ZEUS calorimeter

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
37
eRHIC - Detector design aspects

• Design 1 Forward physics (unpolarized eA
  MPI-Munich group) (4)
• Acceptance
• Full tracking acceptance for ? gt 0.75 - No
  acceptance in central region ? lt 0.5
• Q2 acceptance down to 0.05GeV2 (Full W range) -
  Full acceptance down Q20GeV2 for Wgt80GeV
• High x Electron (Q2) and Jet (x) to determine
  event kinematics

I. Abt, A. Caldwell, X.
Liu, J. Sutiak, MPP-2004-90, hep-ex
0407053

• Track efficiency
• Full efficiency below 6GeV for ? gt -8
• For larger energies, full efficiency for ? gt -5

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
38
eRHIC - Detector design aspects

J. Pasukonis, B.S.

• Design 2 General purpose (unpolarized/polarized
  ELECTRon-A) (1)

• Detector concept
• Hermetic detector system inside 3m machine
  element free region
• Starting point
• Barrel and rear EM system e.g. Si-Tungsten
  (Similar to Design 1)
• Forward EM/hadron calorimeter e.g.
  Pb-scintillator
• Tracking system and barrel EM inside solenoidal
  magnetic field
• Tracking system based on high-precision Si
  (inner) and micro-pattern technology (Triple-GEM)
  (outer)

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
39
eRHIC - Detector design aspects

J. Pasukonis, B.S.

• Design 2 General purpose (unpolarized/polarized
  ELECTRon-A) (2)

• ELECTRA detector simulation and reconstruction
  framework
• GEANT simulation of the central detector part
  (tracking/calorimetry) available Starting point
• Calorimeter cluster and track reconstruction
  implemented
• Code available through CVS repository
• http//starmac.lns.mit.edu/erhic/electra/
• To-do-list
• Evaluate and optimize detector configuration - In
  particular Type of magnetic field configuration
• Design of forward tagging system and particle ID
  systems
• Rear detection systems
• For eA events Optimize forward detector system
  for high-multiplicity environment

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
40
eRHIC - Detector design aspects

J. Pasukonis, B.S.

• Design 2 General purpose (unpolarized/polarized
  ELECTRon-A) (3)
• Simulated ep DIS event (LEPTO)

Lower Q2 acceptance 0.1GeV2
Side view

• DIS generators
• used so far
• LEPTO
• DJANGO

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
41

eRHIC - Detector design aspects
E. Kistenev
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
42

eRHIC - Detector design aspects

• IR region
• Design concept Forward physics (unpolarized eA
  MPI-Munich group)
• Machine element free-region approx. 5m
• Physics program could be accomplished at lower
  luminosity
• Design concept General purpose
  (unpolarized/polarized ELECTRon-A)
• Machine element free-region approx. 3m
• Physics program requires high luminosity
  operation
• Synchrotron radiation background
• Optimize beam pipe shape
• Accommodate synchrotron radiation fan generated
  by e-beam as a result of beam separation
• Maximize detector acceptance
• Design of absorber and masking system
• Beam-gas background
• Bremsstrahlung of electrons with residual gas and
  proton-beam gas background
• Shielding and collimation
• Minimize dead-material close to the beam
• Good vacuum conditions crucial

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
43
Concluding remarks

• Preparation of eA case
• eA MC generators
• VNI (Not tested - requires comparison to LEPTO)
• Can we get VENUS?
• Incorporate saturation effects in existing MC
  generators?
• ELECTRA Detector simulation and reconstruction
  framework available
• Kinematic reconstruction
• Low x Electron
• High x Use hadronic final state. How well does
  this work for eA?
• Multiplicity eA vs. ep, in particular in the
  forward direction?
• Luminosity measurement?
• Simulation of F2A? Which range in A?
• Beyond F2A FL and VM production
• Global analysis of gluon distribution function

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
44
Concluding remarks

• Critical eRHIC RD issues
• Calorimetry Compact, high resolution, e/h
  separation
• Tracking High-rate, low dead material, high
  occupancy (Forward direction)
• Forward/Rear instrumentation Compact, high
  radiation environment
• Magnetic field configuration Combination of
  solenoid and dipole-type configuration
• DAQ/Trigger system Multi-level trigger system
• Background Synchrotron radiation absorber and
  shielding

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
45
Concluding remarks

ep/eA (Represented by two leaders in
DIS/Rel.Heavy Ion)
eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
46
Hadronic Calorimetry

• ZEUS UCAL Module design
• Depleted Uranium-Scintillator Calorimeter
• 3.3 mm DU plates clad in stainless steel
• 2.6 mm scintillator
• e/h 1 (EM response hadronic)
• Compensating (energy from neutrals)
• 18 / vE - Electromagnetic resolution
• 35 / vE - Hadronic resolution
• Timing resolution 1.5ns / vE
• Modules 20cm wide
• Various heights 220 - 460cm
• Coverage and depth
• Forward (FCAL) (7?) 2.2 - 39.9
• Barrel (BCAL) 36.7 - 129.1
• Rear (RCAL) (4?) 128.1 - 176.5

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
47
Hadronic Calorimetry

• Details on ZEUS UCAL dismantling and handling
• Formal agreement between DESY and DOE that UCAL
  has to be shipped back to the US (DOE owns U
  material)
• Shipping costs will be covered by DESY and DOE
• Current plan in case of no further usage
• Shipment on container ship without further
  pre-caution of further re-usage (Transport
  several modules in one container)
• Quotations are currently being discussed with
  several companies in Germany
• Shipment will be carried out to Utah under
  supervision of ANL and DOE
• Handling of UCAL modules in Utah will be carried
  out by a DOE contractor for long-term underground
  storage
• Dismantling of the ZEUS detector will start in
  July 2007
• Current plan Dismantle UCAL modules first with
  short-term storage in ZEUS experimental hall
• Subsequent shipment of modules to US (Utah) over
  the course of lt 1 year

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
48
Hadronic Calorimetry

• Note to BNL management under preparation by MIT
  group
• Excellent instrument which is fully functional
  with the best hadronic energy resolution
• Idea Re-use ZEUS UCAL for the forward hadronic
  calorimeter
• Note Uranium material belongs to DOE and has to
  be shipped back the US
• Part to achieve a cost effective solution for a
  detector at eRHIC
• Shipment has to be carried out differently than
  in case of no further usage
• One module per container
• Special transport frames and shock absorbers
• Difference in cost compared to no further usage

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow
49
Hadronic Calorimetry

• Expression of interest Transport ZEUS UCAL
  modules to BNL for EIC
• Decide on FCAL/RCAL modules for optimal coverage
• Transport frames could be assembled at MIT-Bates
• Coordination D. Hasell (MIT)
• Difference in cost compared to no further usage
  would have to be covered by BNL (lt 100k)
• Agreement from DESY and ZEUS management Local
  engineering help will be provided by ZEUS for
  storage and transport to container ship
  (Compensation 1-2 technicans for period of 1-2
  months)
• Shipment of UCAL modules to BNL
• Locate area in AGS experimental hall area for
  storage and test over several years
• Test and evaluation of performance under
  leadership of MIT (Coordination D. Hasell)
• Note Cost factor 20M (1990) (Inflation (2005)
  30M) (No labor cost included!). Including labor
  cost assuming a factor 2 would result in 60M
  (2005) ZEUS modules will be provided at no
  further cost!

eA eRHIC meeting BNL, October 20, 2006
Bernd Surrow