physics requirements and solenoid description · 2011-10-11 · physics requirements and solenoid...

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)


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


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


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

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0

50

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−50 0 50 100 150 200 250 300 350 400

00.25

0.50.75

11.25

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-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


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!


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


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


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


physics requirements and solenoid description · 2011-10-11 · physics requirements and solenoid...

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