Detector Upgrades and Responsibilities

Hampton University, Hampton, VA 23668, USA

BLAST@DORIS Workshop, DESY, March 31, 2008

Michael Kohl

Proposed Experiment

• Electrons/positrons (100mA) in multi-GeV storage ringDORIS at DESY, Hamburg, Germany

• Unpolarized internal hydrogen target (buffer system)3x1015 at/cm2 @ 100 mA → L = 2x1033 / (cm2s)

• Large acceptance detector for e-p in coincidenceBLAST detector from MIT-Bates available

• Redundant monitoring of luminositypressure, temperature, flow, current measurementssmall-angle elastic scattering at high epsilon / low Q2

• Measure ratio of positron-proton to electron-protonunpolarized elastic scattering to 1% stat.+sys.

OLYMPUS

pOsitron-proton and

eLectron-proton elastic scattering to test the

hYpothesis of

Multi-

Photon exchange

Using

DoriS

Control of Systematics

Luminosity monitors

BLAST @ DORIS

10o

• Change BLAST polarity once a day• Change between electrons and positrons once a day• Left-right symmetry

Control of Systematics

i = e+ or e-j= pos/neg polarity

Geometric proton efficiency:

Ratio in singlepolarity j

Geometric lepton efficiency:

Control of Systematics

• Change between electrons and positrons every other day• Change BLAST polarity every other day• Left-right symmetry

Super ratio:

Cycle of four states ijRepeat cycle many times

Luminosity Monitoring

• Measure Lij relative and continuously

• Pressure, temperature, flow, current measurements

• Forward-angle (high-epsilon, low-Q) elastic scattering (e+ = e-)

• Moller scattering• …

At forward angle:

Forward Elastic Luminosity Monitor

• Forward angle electron/positron telescope with good angular and vertex resolution

• Coincidence with proton in BLAST

• High rate capability

GEM technology?

MIT protoype:

Telescope of 3 Triple GEM prototypes (10 x 10 cm2) using TechEtch foils

F. Simon et al., IEEE2007, arXiv:0711.3751

Forward Elastic Luminosity Monitor

• Two symmetric GEM telescopes at 10o

• Sub-percent luminosity measurement per hour for all energies

• 22.5 msr = 30 x 30 cm2 at 200 cm distance• Two GEM layers with ~0.1 mm resolution with ~10 cm gap

→ Vertex resolution (z) of ~1cm at 10o

• Two-photon effect negligible at high- / low-Q2

MIT GEM-Lab

• GEM R&D at MIT Laboratory for Nuclear Science (LNS)and MIT-Bates Linear Accelerator

• Upgrade of STAR forward tracker

Richard Milner (Principal Investigator)Bernd Surrow (Assistant Professor since 2003)Douglas Hasell (Principal Research Scientist)Frank Simon (Postdoc, previously COMPASS)Jim Kelsey (MIT-Bates Mechanical Engineering)Miro Plesko (MIT-Bates Electronic Engineering)

• F.S. now Junior Group Leader at MPI Munich

HU Nuclear Physics Group

Cynthia Keppel (Endowed Professor)Eric Christy (Associate Professor)Rolf Ent (Adjunct Professor)Antje Bruell (Adjunct Professor)M.K. (Assistant Professor)

Howard Fenker (Jlab)

Providing GEM technology

• Collaboration HU-MIT

• Goal: Establish HU/Jlab GEM R&D Center

– Howard Fenker / Bonus collaboration– Thia Keppel / Medical physics applications– Proton Cancer Therapy Center under construction at HU – Augment 12 GeV program at Jlab

– By building C0 cylindrical GEM tracker for TREK, provide technology for 12 GeV program at Jlab

– Luminosity monitors for OLYMPUS– Contributions to OLYMPUS further program?

Principle of GEM Detectors

• Copper layer-sandwiched kapton foil with chemically etched micro-hole pattern

gas amplification in the hole

• GEM = Gas Electron Multiplier introduced by F. Sauli in mid 90’s, F. Sauli et al., NIMA 386 (1997) 531

GEM foils

70 µm

140 µm

70 µm

55 µm

5 µm

50 µm``

Typically 5m Cu on 50m kapton

~104 holes/cm2

Chemical etching• R. De Oliveira (CERN-EST)• TechEtch (MIT, BoNuS)• 3M Corporation

Laser drilling• Tamagawa (RIKEN)

Multi-GEM Detectors

• GEMs can be cascaded for higher gain• Gain of 104 needed for efficient MIP detection

GEM 1

GEM 2

ED

ET

EI

DRIFT

READOUT

DRIFT

TRANSFER

INDUCTION

GEM 1

GEM 2

ED

ET1

EI

DRIFT

READOUT

DRIFT

TRANSFER 1

INDUCTION

GEM 2

ET2 TRANSFER 2

Double GEM Triple GEM

C. Buettner et al., Nucl. Instr. and Meth. A 409(1998)79S. Bachmann et al., Nucl. Instr. and Meth. A 443(1999)464

TREK/E06 Tracking Upgrade

12 Planar GEMs (C1) between CsI and C2 1 Cylindrical GEM (C0) in replacement of former C1

70 µm

140 µm

GEM technology

Time Reversal Experiment with Kaons: Search for PT (K3)

C0 Cylindrical GEM for TREK

300 mm

140

mm

160

mm

BoNuS

• Radial TPC (8-12 cm in./out. Diameter, 20cm active length)• Ran in CLAS end of 2005, first experiment to use cylindrical GEM detector• Further development planned for CLAS and Jlab-12 GeV→ Howard Fenker

• H. Fenker et al., submitted to NIM (2008)

BoNuS

• Tag neutron initial momentumby measuring spectator proton at low momentum-> neutron structure

• Tag energetic pions by tracking low-momentum ’s and tritons in pion production-> pion cloud study

Barely off-shell Nuclear Structure

OLYMPUS Detector / Upgrades

• Crucial components for OLYMPUS

BLAST core detector (WC+CC+SC)Additional e+,e- discrimination?Luminosity monitoring

Further use of BLAST @ DORIS

• Polarized H/D target (ABS)

• Neutron detectors

• Recoil detectors

• Inner tracker

• Forward-angle tracking

• Forward tagging system/quasireal photons

OLYMPUS Responsibilities

• DORIS - DESY• Transfer of BLAST detector – MIT/Bates• BLAST Cerenkov counters – ASU• BLAST Time-of-flight scintillators – UNH• Unpolarized gas target – MIT/Bates• Luminosity monitors – HU/Jlab

• Electron/positron ID• Maintenance and operation of detector components• Simulation tasks• Analysis tasks