Detector & Interaction Detector & Interaction Region Concepts for DES Region Concepts for DES

and SIDISand SIDIS

Pawel Nadel-TuronskiPawel Nadel-Turonski

Jefferson Lab, Newport News, VAJefferson Lab, Newport News, VA

EICC meeting, January 10–12, 2010, Stony Brook, NYEICC meeting, January 10–12, 2010, Stony Brook, NY

12 January 2009 2

Outline

1. Deep Exclusive Reactions1. Deep Exclusive Reactions

2. Detector and Interaction Region Concepts2. Detector and Interaction Region Concepts

3. SIDIS3. SIDIS

• Kinematics at various proton energies• Acceptance and PID

• Only brief discussion

• Taking advantage of crossing angle and symmetric kinematics• Detector implementation

12 January 2009 3

Exclusive meson kinematics – p

• Meson kinematics integrated over all Q2

– Vertical lines at 30° (possibly up to 40°) indicate transition from central barrel to endcaps

– Horizontal line indicates maximum meson momentum for π/K separation with a DIRC

• Problem: cross section falls rapidly with Q2

– Higher Q2 is needed due to factorization requirements for GPD determination, but plots shown are dominated by photoproduction.

Tanja Horn

ep → e'π+n

4 on 12 GeV 4 on 30 GeV 4 on 250 GeV

12 January 2009 4

Exclusive meson kinematics – Q2

Tanja Horn

ep → e'π+n

4 on 12 GeV 4 on 250 GeV4 on 60 GeV

• “Asymmetric” kinematics: 250 GeV protons– high Q2 mesons are detected in ion side endcap

• May suggests slightly different optimizations, but no major differences

• “Symmetric” kinematics: 12 - 60 GeV protons– high Q2 mesons are detected in the central barrel

12 January 2009 5

Exclusive meson kinematics – p at higher Q2

Tanja Horn

4 on 250 GeV4 on 30 GeV

no Q2 cut no Q2 cut

Q2 > 10 GeV2Q2 > 10 GeV2

• The meson momentum distribution has a strong Q2-dependence

• DIRC not useful at 250 GeV. Large bore angle (RICH acceptance) helpful?

• No mesons at small angles where solenoid resolution is poor (both kinematics).

• Momentum resolution (dp/p ~ p from tracking), a challenge at 250 GeV?

12 January 2009 6

“Symmetric” kinematics – 4 on 30 GeV

Tanja Horn

ep → e'π+n

recoil 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

12 January 2009 7

For Q2 > 10 GeV2, 4 on 30 or 250 GeV is quite different

Tanja Horn

recoil baryonsscattered electronsmesons

4 on

250

GeV

4 on

30

GeV

t/t ~ t/Ep lower Ep better

DIRC not useful

very high momenta

electrons in central barrel, but p different

2.5°

0.5°

Exclusive electron kinematics – Q2

Tanja Horn

ep → e'π+n

4 on 250 GeV4 on 12 GeV 4 on 60 GeV

• Q2-distribution similar for all proton energies– Electron momenta are very different on ion side!

• Electrons with Q2 > 5 GeV2 will generally be detected in the central barrel

• Higher electron energies shift distribution to the left

electrons with beam energy

12 January 2009 9

1. (Crab) crossing angle and symmetric kinematics1. (Crab) crossing angle and symmetric kinematics

2. Detector Challenges2. Detector Challenges

3. Accelerator benefits3. Accelerator benefits

• Allow a compact forward ion detector• Can be used to eliminate synchrotron radiation• Produce electron and meson momenta comparable to CLAS

– Good momentum resolution– Good particle identification

• Reduced chromaticity (f/β*)

• Optimization of forward ion detection• PID at higher electron enegies (5-10 GeV)

DES detector and Interaction Region concepts

12 January 2009 10

Dipole coils

Forward detection with crossing angle

• Electrons on solenoid axis, ions cross at 3° (50 mrad)

– Improves hadron tracking at small angles, also in solenoid (v x B = 0 on axis)

– Outer radius of electron FFQs about 10 cm if 4-6 m from IP

• Common forward dipole has some disadvantages

– Produces synchrotron radiation (field exclusion plates?)

– Field settings according to electron energy, not ion energy

– Requires downstream steering for ions before FFQs

– Introduces a large amount of dead material close to bore

– Even a 1 m diameter aperture offers only 9° incoming acceptance

ions

solenoid

electron FFQs

ion FFQs

3°

0°

dipole

(approximately to scale)

Scattered positive and incoming negative particles bent “down”

additional ion dipole(s)detectors

electrons

5 m 3.5 m 3 m

IP

Alternative dipole geometry

12 January 2009 11

Forward detection optimized for DES

• Downstream dipole on ion beam line has several advantages

– No synchrotron radiation

– Positive particles are bent away from the electron beam

– Long recoil baryon flight path gives access to low -t

– Does not interfere with RICH and forward calorimeters

• Used as veto for DES in symmetric kinematics

• Improved hermeticity and lower backgrounds?

exclusive mesons

2.5°

recoil baryons

solenoid

electron FFQs3°

0°

ion dipole w/ detectors

(approximately to scale)

ions

electrons

IP

detectors

ion FFQs

• -t coverage for neutrons

– 9 m flight path from IP to ion FFQ sufficient at 30 GeV

12 January 2009 12

4 m

Forward ion (proton) detection at 250 GeV

• If luminosity is only high at max ion energy, asymmetric kinematics may be unavoidable

recoil baryons

0.5°

• Achieving low-t coverage comparable to symmetric kinematics will require long unobstructed flight paths

– 45 m vs. 9 m (for neutrons; for protons only taking geometry into account)

14 December 2009 13

Solenoid yoke integrated witha hadronic calorimeter anda muon detector

EM calorimeter

Conceptual sketch of main detector layout

EM

cal

orim

eter

RICH (DIRC?)

Tracking

RIC

H

Had

roni

c ca

lori

met

er

Muo

n D

etec

tor?

HT

CC

EM

cal

orim

eter

ions

electrons

(not to scale)

Time-of-flightdetectors shownin green

• IP is shown at the center, but can be shifted (left)

– Determined by desired bore angle and forward tracking

DIRC would have thinbars arranged in acylinder with mirrorsand readout after theEM calorimeteron the left

12 January 2009 14

DES (and SIDIS) at higher energies – DIRC or RICH?

• With 12 GeV CEBAF, MEIC@JLab has the option of using higher electron energies

– DIRC no longer sufficient for π/K separation

• RICH would extend diameter of solenoid from approximately 3 to 4 m

– Main constraint since bore angle is not an issue in JLab kinematics

4 on 30 GeV

s = 480 GeV2

5 on 50 GeV

s = 1000 GeV2

(10 on 50 GeV)

s = 2000 GeV2

• RICH based on ALICE design might push the limit from 4 to 7 GeV

– Requires a more detailed study

Q2 >

10

GeV

2

12 November 2009 15

C. Weiss Lum

inos

ity [

cm-2

s-1

]

s [GeV2]

1035

1034

1033

1032

10 100 1000 10000 100000

COMPASS

JLAB6&12HERMESENC@GSI

(M)EICMeRHIC

DIFFDIS

EW

DES

JETSSIDIS

Nucleon structure beyond the valence region

• MEIC optimized for s of 250-1000 GeV2

(see talks by T. Horn and C. Weiss)

12 January 2009 16

• 4T solenoid with 3-4 m diameter

• Hadronic calorimeter and muon detector integrated with the return yoke (c.f. CMS)

• TOF for low momenta

• π/K separation options

– DIRC (BaBar) up to 4 GeV

– RICH (ALICE) up to 7 GeV?

• e/π separation options

– Lead-tungsten

• Very good resolution

– Tungsten powder / scintillating fiber

• Very compact, 6% resolution

TrackingTracking

Solenoid Yoke, Hadron Calorimeter, MuonsSolenoid Yoke, Hadron Calorimeter, Muons

Particle IdentificationParticle Identification

• Central Tracker

– Radius: at least 80 cm assumed

– Microchannel or silicon detectors?

• CLAS12: Micromegas

– Integrated vertex tracker

Central detector

12 January 2009 17

• 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)

• Ring-Imaging Cerenkov (RICH)

• Time-of-Flight Detectors

• Electromagnetic Calorimeter

• Hadronic Calorimeter

• Muon detector (at least small angles)

– Important for J/Ψ photoproduction

TrackingTracking

Electron side (left)Electron side (left)

Ion side (right)Ion side (right)

• Forward / Backward

– IP may be shifted to electron side

• Lower momenta

– 3 regions of drift chambersg

Detector endcaps

12 January 2009 18

• Synchrotron radiation is not an issue for outgoing electrons– Can use strong dipole to cover small scattering angles

• Still need steering dipole on either the electron or ion beam line to compensate for independently adjustable beam energies

• Ion quads can be placed closer on electron side.

Low-Q2 tagging? – very conceptual!

3°

0°

“tagger” detector(not to scale)

steering dipolesion FFQs

electron FFQs

dipole

ions

electrons

12 November 2009 19

Diffractive and SIDIS (TMDs)4 on 250 GeV4 on 50 GeV

diff

ract

ive

DIS

• Diffractive kinematics for 4 on 50 are still quite symmetric

• Both reactions produce high-momentum mesons only at small angles

• DIRC and forward RICH seem sufficient

• With 3° crossing angle, solenoid and ion-only dipole (5 m from IP) also seem adequate

• To do: study SIDIS kinematics in many bins to see actual coverage!

12 November 2009 20

Summary

• Deep exclusive reactions (GPDs) and Semi-Inclusive DIS (TMDs) are essential for studying nucleon/nuclear structure

• Symmetric kinematics are ideal for probing gluons and sea quarks, but require high luminosities (1034) at medium energy

• A 3° crossing angle allows optimization of the forward detection

12 November 2009 21

Backup

• The central detector geometry is currently being implemented in GEANT4– CLAS12 simulation engine (GEMC) is used

– Detector elements modeled down to digitization level

– Standard CLAS tools can be used for analysis of simulated data

– At the moment only the solenoid field has been added

– Will be extended to include beam line on both sides

– Short- and long term event reconstruction options are being pursued

Status of detector simulations at JLab

• The JLab simulation working group is also developing– Event generators for various processes

– A Fast Monte Carlo to explore acceptance and resolution requirements

12 January 2009 23

actual (simulated)

ideal solenoid

JLab Hall D: 1.8T solenoid

Tracking resolution

12 November 2009 24

JLab CLAS12

EIC@JLab: electron beam envelopes across FF quads at nominal distance

9.25

Thu Oct 08 18:40:22 2009 OptiM - MAIN: - N:\bogacz\ELIC\MEIC\Optics\IR\ele\e_6m_R_4.opt

10

10

Siz

e_

X[c

m]

Siz

e_

Y[c

m]

Ax_bet Ay_bet Ax_disp Ay_disp

3 GeV

50 cm p50 cm120 cmG[kG/cm]=-1.14 G[kG/cm]=0.71 G[kG/cm]=-0.75600 cm

IP

12 November 2009 26

x ~ Q2/ysmEIC at JLab, 11 on 60 GeV

JLab 12 GeV

H1

ZEUS

HERA, y=0.004 mEIC 3 on 20, y=0.004

x

Q2 (

GeV

2 )

s The MEIC@JLab will overlap with HERA and JLab 12 GeV at a comparable luminosity.

mEIC@JLab – kinematic coverage

12 November 2009 27

pp

ppe m

pII

ε

Luminosity

L

s

detector limit synchrotron radiation limits electron current

space charge limits ion current at low momentum

ERL-RingRing-Ring

Luminosity scales with ion momentum if cooling can shrink the ion beam (ε

p)

e p

A medium-energy ring-ring collider provides a high luminosity over a range in s, not only at the end point.

Luminosity