E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 1 Physics Requirements and Solenoid Description E.Chudakov 1 1 JLab Solenoid Director s Review, JLab, Oct 2010
E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 2 Hall D Physics: Spectroscopy in a Polarized Photon Beam Radiator Top View Coherent Bremsstrahlung photon beam Pair Spectrometer Counting House Photon Beam dump Tagger 75 m Electron beam / dump Collimator Solenoid- Based detector Physics: search for hybrid mesons in γp at 9 GeV Nearly 4π coverage for γp Xp, X light mesons final states p,π ±,π γγ, 0.3 5 GeV/c, multiplicity > 4 uniform acceptance needed for PWA Enough momentum/energy resolution to: separate γp Xp and γp Xpπ minimize contamination by wrong partial waves in PWA Solution: Spectrometer based on Solenoidal magnet (decided about 10 years ago)
The Choice of the Magnet Design Feature: Open Yoke - No Endcap γ-detection at θ< 10 with existing LG-calorimeter TOF detectors for charged particles at θ< 10 Space of a gas Cherenkov detector Requires more Amp-turns than magnets with yoke endcaps LASS Solenoid 4 coils Comparable Spectrometers LASS SLAC K ± -beam 11 GeV/c spectroscopy (no γ-detection) Comparable energy range Solenoid: 2.2 T, bore =1.85 m Solenoid: open yoke Small angles: dipole 2.5 T m BABAR, CLEO-II, CDF not available 1.5 T, bore =2.90 m Larger detectors needed E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 3
GLueX Detector Initial coil configuration 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 SLAC 4 years at Los Alamos GlueX: Do we need this field? no gaps between coils FOM 1/(EM Brief review of the physics: background σ search Mass ) for exotic hybrid more open mesons yoke 2.2 T 1.5 T 2.5 longer running Importance of neutral particle detection E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 4
Adaptation of the LASS magnet 4 separate coils 2 1 3 4 coils coil 1 New parts baffles Changes to the Magnet The front endcap is opened similar to the back endcap Simplifies detector installation, space for readout cables Lower field in front of the magnet - OK Change of forces Fill yoke gaps - smaller stray fields Force compensation: Swap coils #1 and #2 Baffles 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 E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 6 GlueX (Hall D) solenoid basic, 1500A 350 300 250 200 150 100 50 0 50 0 50 100 150 200 250 300 350 400 Z:\home\gen\.wine\my_poisson\GLUEX_SOL\GLUEX_SOL_04.AM 5 12 2010 21:03:52 350 300 250 200 150 100 50 0 B Z, T 2.5 2.25 2 1.75 1.5 1.25 1 0.75 0.5 0.25 0 Coils -200 0 200 400 600 Z, cm 1500 A Lower field at target Z 60 cm is beneficial for acceptance POISSON 2-D simulation: quick and flexible ANSYS 3-D simulation: takes into account azimuthal non-uniformity Consistent results
Problems with the Magnet E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 7 Coil refurbishing was needed to fix known problems: Shorts to ground N2 shield corrosion Various leaks Other problems identified: Pressure safety Mechanical stability of windings tips in coil #2 Potential turn-to-turn shorts Considerably more work than originally anticipated!
Internal Review Nov 2009, IPR Apr 2010 E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 8 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, provide detailed test plan. Subsequent discussions pinpoint two items: Shorts between the coil conductor and supporting strips pose a particular hazard Analysis performed Consideration of a back-up replacement solenoid should go in parallel with analysis, refurbishment, risk mitigation and testing of the existing solenoid. Started
Current Plans E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 9 Continue working on the LASS solenoid: Finish refurbishing the coils (#2 and #3 left) Test every coil separately at the nominal current 1500 A for performance and forces Testing of coil #1 is in progress Work on a new solenoid in parallel with the refurbishment: Prepare the physics requirements Develop a path to final design This review, for consultations with experts in the field Refurbishment plan and test plan - technical risks Time line for completing test and refurbishment Path forward on a possible replacement solenoid
Schedule E.Chudakov Solenoid Review, Oct 2010 Physics Requirements and Description 10 Beam expected in April 2014 Installation schedule: start solenoid installation by Nov 2011 no float left Testing schedule: Still considerable uncertainty on the cooling time and other activities Current estimate: finish testing of all 4 coils by Nov 2011 no float left How to increase the float? Cooling time? Omit the test of Coil #2