first detector concepts for a (m)eic

EIC-IAC @ JLab, November 2009 1

First Detector Conceptsfor a (M)EIC

E.C. Aschenauer


Detector Requirements from Physics

E.C. Aschenauer

ep-physics the same detector needs to cover inclusive (ep -> e’X), semi-

inclusive (ep -> e’hadron(s)X) and exclusive (ep -> e’pp) reactions

large acceptance absolutely crucial (both mid and forward-rapidity) particle identification is crucial

e, p, K, p, n over wide momentum range and scattering angleexcellent secondary vertex resolution (charm)

particle detection to very low scattering angle around 1o in e and p/A direction

in contradiction to strong focusing quads close to IP small systematic uncertainty (~1%/~3%) for e/p polarization

measurements very small systematic uncertainty (~1%) for luminosity

measurement eA-physics

requirements very similar to epchallenge to tag the struck nucleus in exclusive and diffractive reactions.difference in occupancy must be taken into account

EIC-IAC @ JLab, November 2009 3E.C. Aschenauer

Event kinematics scattered lepton

DIS

DIFFRACTIVE

4x50 4x250

175o

179o

withoutmagneticfield

20x250


Event kinematics produced hadrons (p+)

E.C. Aschenauer

DIS

DIFFRACTIVE

4x50 4x250


DIS:smalltheta important

20x250


Recoil Proton for Diffractive events

E.C. Aschenauer

4x50 4x250

20x250

EIC-IAC @ JLab, November 2009E.C. Aschenauer

6

STAR

PHENIX

2 x 200 m SRF linac4 (5) GeV per pass5 (4) passes

Polarized e-gun

Beamdump

4 to 5 vertically separatedrecirculating passes

Cohe

rent

e-

cool

er

5 mm

5 mm

5 mm

5 mm

20 GeV e-beam16 GeV e-beam

12 GeV e-beam

8 GeV e-beam

Com

mon

vac

uum

ch

ambe

r

Gap 5 mm total0.3 T for 30 GeV

(M)eRHICdetector

MeRHIC

detector

10-20 GeV e x 325 GeV p 130 GeV/u Au

possibility of 30 GeV @low current operation

ERL-based eRHIC Design


First ideas for a detector concept

E.C. Aschenauer

Dipole3Tm

Dipole3Tm

Solenoid (4T)

ZDC

FPD

FED// //

Dipoles needed to have good forward momentum resolution Solenoid no magnetic field @ r ~ 0

DIRC, RICH hadron identification p, K, p high-threshold Cerenkov fast trigger for scattered lepton radiation length very critical low lepton energies


IR-Design for MeRHIC I @ IP-2

E.C. Aschenauer

no synchrotron shielding included IP-2: height beam-pipe floor ~6’ (with digging

~10’)

BNL S&T-Review, July 2009 9

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 ~ pAθmin

For beam energies = 100 GeV/n and θmin = 0.08 mrad:

These are large momentum kicks, much greater than the binding energy (~ 8 MeV) Therefore, for large A,

coherently diffractive nucleus cannot be separated from beamline without breaking up

E.C. Aschenauer

species (A) pTmin (GeV/c)

d (2) 0.02Si (28) 0.22Cu (64) 0.51In (115) 0.92Au (197) 1.58U (238) 1.90

?


Detection from hadron beam fragments Tagging from Au fragments and p/n in ep

suppress incoherent scattering / ensure exclusivity neutrons are detected in ZDC protons use magnetic rigidity Au:p 2.5:1

DX magnets disturbs p tagging

E.C. Aschenauer


IR-Design for MeRHIC IP-2

E.C. Aschenauer

no synchrotron shielding included allows p and heavy ion decay product tagging IP-2: height beam-pipe floor ~6’ (with digging ~10’)


Model Detector @ IP-2 in Geant

E.C. Aschenauer

Dipole3Tm

Dipole3Tm

Solenoid (4T)

ZDC

FPD

FED// //

Transfer sketch into Geant and fits in IP-2


MeRHIC Detector in Geant-3

E.C. Aschenauer

DIRC: not shown because of cut; modeled following Babar no hadronic calorimeter in barrel, because of vertical space @ IP-2

Drift Chambers central tracking

ala BaBar

Silicon Stripdetectorala Zeus

EM-CalorimeterLeadGlas

High ThresholdCerenkov

fast trigger on e’e/h separation

Dual-Radiator RICH

ala HERMES

Drift Chambers ala HERMES FDC



E.C. Aschenauer


To Do List

Have done first steps on a detector design Optimizations needed

magnetic fieldsdo we need 4T for solenoid and 3Tm for dipoleoptimize distance Dipole to Solenoidneed to optimize Dipole gap to have enough place for detectors

what radiation length can we tolerate @ low e’ momentum

impact of beam lines through the detector on physicsneed to optimize acceptance at low scattering angle

need acceptance down to 1o

need to include lepton polarimeter in IR design need to include luminosity monitor into IR design choose detector technologies R&D

E.C. Aschenauer

MeRHIC Cost Review – Pre Run

Concept of Electron Compton Polarimeter for MeRHIC

10/07/2009

scattered electronmomentum analyzed in dipole magnet measured with Si or diamond strip detector

pair spectrometer (counting mode)e+e– pair production in variable converter dipole magnet separates/analyzes e+e–

sampling calorimeter (integrating mode)count rate independent Insensitive to calorimeter response 17

eP

ee

D0 magnetD0 magnet

converter

hodoscopes

calorimeter

e

e+ LINACLaser

Elec

tron

dete

ctor


Start immediately at 12o’clock

Detector cost savings have MeRHIC-detector @ IP-12 (size of STAR)

fully staged detector from MeRHIC to eRHIC vertical space much bigger (room for HCal) need to buy magnets only once can stage detector components, i.e. hadronic calorimeter no moving of components (IP2 IP12) systematics reduced same detector for all energies

only advantages


Work done @ JLAB


ions

electrons

solenoid dipole bendingscattered protons “up”

IP withcrossing angle electron FFQs

ion FFQs

Distance from IP to electron FFQ: 6 m to ion FFQ: 9m

Electron FF quad

Distance from IP

length Field strength

Beam size sx@ 3 GeV

Beam size sy@ 3 GeV

Quad 1 6.0 meter 50 cm -1.14 kG/cm

5 mm 4 mm

Quad 2 6.75 meter

120 cm 0.71 kG/cm

8 mm 3 mm

Quad 3 8.7 meter 50 cm -0.75 kG/cm

4 mm 4 mm

Modest electron final focusing quad field requirements quads can be made small

ELIC Detector/IR Layout

E.C. Aschenauer

by R. Ent


8 meters (for scale)

140 degrees

Tracking

TOF

dipole

solenoid

RICH

ECAL

DIRC

HCAL

HTCC

Offset IP?

Ion beame beam

dipole1st (small) electron FF quad @ 6 m

ELIC detector cartoon - Oct. 09

E.C. Aschenauer

Additional electron detection (tracking, calorimetry) for low-Q2 physics not on cartoon

by R. Ent


Central 4T solenoid with 5 meter length and 4 meter ID Need to add good particle identification detectors up to 40 degrees on ion side drives large ID to keep this area “open” 4T field renders O(1%) or better momentum resolution for particles with momentum < 10 GeV (and angles > 40 degrees)

Optimize detector to detect particles down to (at least) one degrees Add 2-3 Tm dipole field to improve momentum resolution at forward angles. Two solutions: add dipole, or add dipole to solenoid? Can in principle also have split dipole, with different polarity before/after IP, if this helps accelerator design.

5T solenoid with 0.6T dipole winding:Integrated transverse (By) field strength

@ 90 degrees 10.9 Tm@ 40 degrees 15.3 Tm@ 1 degree 1.4 Tm

May present alternate solution if space is at a premium & 1.4 Tm sufficient field strength at 1o.

Note: all configurations iron free at moment

Dipole coils

ELIC Detector Magnetic Field

E.C. Aschenauer

by R. Ent


kk'

ZP ZP'

q'q

Mm

e + AZ e’ + AZ’ + (,,J/)Determining exclusivity requires

tagging the nucleus in the final state. The typical scale of transverse momentum transfer is given by the rms nuclear radius.

(for nuclei from 4He to 20Ne, this scale ranges from 125 MeV/c to 75 MeV/c)

Recoil Tagging in Deeply Virtual Exclusive Reactions on Nuclei

E.C. Aschenauer

For Nuclei ≥ 4He, the recoil nucleus is – INSIDE the transverse admittance of the FF Quads

• Qms ≈ 1 mr PA,transverse ≈ Z·(60 MeV/c) (for 60 GeV ion beam)

• Beam spread is larger than 1/RA scale for nuclear imaging.• Z·(60 MeV/c ) > (0.2 GeV/c)/A1/3 (≥75 MeV/c for AZ< 20Ne)

– OUTSIDE the longitudinal admittance of the ring lattice!!! The nuclei may be detectable at high resolution with far forward tracking in the lattice by having large dispersion ELIC study

by Ch. Hyde


Far Forward Ion Tagging at (60 GeV/c) Z Sample optics at token Roman Pot Telescope position

ELIC typical: Dispersion D = 1m, Beta function b@RP = 2m ELIC typical: (x,Q) = (250 mm, 125 mr) rms Use a 10sx Beam Stay Clear (BSC) distance 2.5 mm Ions are detectable for |dPA||/PA| > BSC/D = 2.5 x 10-3

Skewness 2z (~x/A) of DVCS = long. momentum fraction of a nucleon in projectile ion.

Skewness acceptance: 2z > (2.5x10-3)A 0.05 for 20Ne. Assumption: 1m drift with 100 mm spatial resolution

dQ = 100 mr equal to beam Qrms. PA’ Momentum Resolution = sx/D = 2.5 x 10-4.

D|| = (k-k’-q’)|| = (PA-PA’)||

s(D||) = (4 x 10-4)(30 GeV/c) A = (12 MeV/c) A Exclusivity constraint D2 = 2MA (PA’-PA)

Using ELIC arc as spectrometer to a longitudinal momentum transfer resolution of 10-4 by increasing dispersion @ IR will be explored in more detail

E.C. Aschenauer

by Ch. Hyde


BACKUP


Event kinematics scattered lepton

E.C. Aschenauer

DIS

DIFFRACTIVE

4x50 4x250

175o

20x250

179o



Event kinematics produced hadrons (p+)

E.C. Aschenauer

DIS

DIFFRACTIVE

4x50 4x25020x250


DIS:smalltheta important


Zeus @ HERA I

E.C. Aschenauer


Zeus @ HERA II

E.C. Aschenauer


Hera I vs. Hera II

E.C. Aschenauer

Focusing Quads close to IPProblem for forward acceptance


A Detector for Diffraction and lox-x Physics

E.C. Aschenauer

e

p

HadronicCalorimeter

EM Calorimeter

Si tr

ackin

g

stat

ions

Compact – fits in dipole magnet with inner radius of 80 cm.Long - |z|5 m

Design by Allen Caldwell:

2x14 Si tracking stations

first detector concepts for a (m)eic

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