Physics Requirements and Solenoid Description
E.Chudakov1
1JLab
Solenoid Director’s Review, JLab, Oct 2010
E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 1
Hall D Physics: Spectroscopy in a Polarized Photon Beam
Hall D Tagger and Beamline Review, Nov. 19-20, 2008, Newport News 5
Top View
75 m
Tagger Area ExperimentalHall D
Electron beam / dump
Coherent Bremsstrahlungphoton beam
Solenoid-Based detectorCollimator
PhotonBeam dump
Counting HouseRadiator
PairSpectrometer
Collimator Cave
II. Coherent Bremsstrahlung Beam Line
Coherent bremsstrahlung beam contains both coherent and incoherent components.
Only the coherent component is polarized. Incoherent component is suppressed by narrow collimation.
Tagger
Physics: search for “hybrid” mesons in !p at !9 GeVNearly 4" coverage for !p " Xp, X " light mesons
final states p, !±, !! ! "", 0.3" 5 GeV/c, multiplicity > 4uniform acceptance needed for PWA
Enough momentum/energy resolution to:separate "p ! Xp and "p ! Xp!minimize contamination by wrong partial waves in PWA
Solution: Spectrometer based on Solenoidal magnet(decided about 10 years ago)
E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 2
The Choice of the Magnet
Design Feature: Open Yoke - No Endcap
!-detection at # < 10! with existing LG-calorimeter
TOF detectors for charged particles at # < 10!
Space of a gas Cherenkov detector
Requires more Amp-turns than magnets with yoke endcaps
LASS
Solenoid4 coils
Comparable Spectrometers
LASS SLAC K±-beam 11 GeV/cspectroscopy (no !-detection)
Comparable energy rangeSolenoid: 2.2 T, bore !=1.85 mSolenoid: open yokeSmall angles: dipole 2.5 T·m
BABAR, CLEO-II, CDF not available1.5 T, bore !=2.90 mLarger detectors needed
E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 3
GLueX Detector
Overview - Alex DzierbaHall D
Calorimeter Review1
Hall D/GlueX Calorimeter ReviewOverview and Physics Motivation
Alex R. DzierbaIndiana U and Jefferson Lab
1. Brief review of the physics: search for exotic hybrid mesons
2. Importance of neutral particle detection
3. Role of calorimetry and performance metrics
Initial coil configuration
Do we need this field?FOM # 1/(EMbackground · $Mass)
2.2 T$ 1.5 T$ %2.5 longer running
Design
based on LASS magnet
B=2.2 T central
ID=2 m, L=4 m
4 separate coils
Built at SLAC in 1971
Used:10 years at SLAC4 years at Los Alamos
GlueX:no gaps between coilsmore open yoke
E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 4
Adaptation of the LASS magnet
Thomas Jefferson National Accelerator Facility Page 22
IPR September 2224, 2009
Solenoid
• Coil 1 (Jlab) : short fixed, the coil is reassembled• Coil 3 (IUCF) : new LN2 shield is being installed• Coil/yoke configuration modified - reevaluation of the forces
Minimizing the forces and mitigation of potential problems: coils 1 and 2 are swapped steel baffles added to the yoke reinforcement of coil 2 is being evaluated
• Equipment for the controls is being purchased (12 GeV CR09-27)• Preparations for individual coil testing in FY10
coils
baffles
coil 1
4 separate coils
Coil refurbishing on BIA (operations)
2 1 3 4
New parts
Changes to the MagnetThe front endcap is opened similar to the back endcap
Simplifies detector installation, space for readout cablesLower field in front of the magnet - OKChange of forces
Fill yoke gaps - smaller stray fieldsForce compensation:
Swap coils #1 and #2Baffles
Run at 1500 A to produce 2.2 T (LASS ran at 1600 A)E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 5
Field Simulation
GlueX (Hall D) solenoid − basic, 1500A
Z:\home\gen\.wine\my_poisson\GLUEX_SOL\GLUEX_SOL_04.AM 5−12−2010 21:03:52
0
50
100
150
200
250
300
350
0
50
100
150
200
250
300
350
−50 0 50 100 150 200 250 300 350 400
00.25
0.50.75
11.25
1.51.75
22.25
2.5
-200 0 200 400 600Z, cm
B Z, T
Coils
1500 ALower field at target Z!60 cmis beneficial for acceptance
POISSON 2-D simulation: quick and flexible
ANSYS 3-D simulation: takes into account azimuthal non-uniformity
Consistent results
E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 6
Problems with the Magnet
Coil refurbishing was needed to fix known problems:
Shorts to groundN2 shield corrosionVarious leaks
Other problems identified:
Pressure safetyMechanical stability of windings’ tips in coil #2Potential turn-to-turn shorts
Considerably more work than originally anticipated!
E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 7
Internal Review Nov 2009, IPR Apr 2010
Internal review Nov 2010 (S. St.Loren, B. Schneider, P. Brindza)
Observations: New magnet cost 3.6-6M, not in time for CD-4;Old magnet: Technical problems, but no obvious showstopper
Refurbishment recommendations: clarify physics requirements, providedetailed test plan.
Subsequent discussions pinpoint two items:
Shorts between the coil conductor and supporting strips pose aparticular hazardAnalysis performed
Consideration of a back-up replacement solenoid should go in parallelwith analysis, refurbishment, risk mitigation and testing of the existingsolenoid.Started
E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 8
Current Plans
Continue working on the LASS solenoid:
Finish refurbishing the coils (#2 and #3 left)Test every coil separately at the nominal current 1500 Afor performance and forcesTesting of coil #1 is in progress
Work on a new solenoid in parallel with the refurbishment:
Prepare the physics requirementsDevelop a path to final design
This review, for consultations with experts in the field
Refurbishment plan and test plan - technical risksTime line for completing test and refurbishmentPath forward on a possible replacement solenoid
E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 9
Schedule
Beam expected in April 2014
Installation schedule: start solenoid installation by Nov 2011no float left
Testing schedule:
Still considerable uncertainty on the cooling time and other activitiesCurrent estimate: finish testing of all 4 coils by Nov 2011no float left
How to increase the float?
Cooling time?Omit the test of Coil #2
E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 10