CLAS12 Central Detector Overview and Integration

Thomas Jefferson National Accelerator Facility Page 1

CD Workshop Dec 2-3, 2009

CLAS12 Central DetectorOverview and Integration

David Kashy Hall B Lead Engineer

CLAS CD Workshop Saclay

December 2-3, 2009



Outline

• System Overview• Solenoid and Support• HTCC and Moeller Shields• CTOF and Support• SVT and support• Summary/Conclusion



Hall B Overview

Hall B Space Frame

Hall B – 98’ Diameter

20 Ton Polar Crane

Beam entry tunnel

Beam dump tunnel

Cryogenic Supply and Return Line



CLAS12 Detectors

Silicon Vertex Tracker

Central Time of Flight

Solenoid

High Threshold Cerenkov

3 Regions of Drift Chambers

Torus

3 Panels of Time of Flight –1a & 2 reused

from CLAS

Low Threshold Cerenkov – Reused

from CLAS

Electromagnetic Calorimeter –

Reused from CLAS

Pre-Shower Calorimeter



Solenoid

• Purposes are:– Central field for tracking– Provide magnetic shielding of Moeller

Electrons• Peak field 5T• Homogeneous central region 1e-4 in

Ø =25mm L = 40mm • Limited fringe field at locations of

High Threshold Cerenkov PMT’s • Contract awarded to Wang NMR

11/20/2009• Solenoid supported by 3 legged cart.

Solenoid Lead can and Cryo reservoir

Magnet Cryostat



Central Detectors

• Central tracker and Time-of-Flight detectors are attached directly to the solenoid. This provides stable reliable support that will limit external vibrations since its mass is very large ~20tonn



Plans for Mounting to Solenoid

SVT MountsCTOF Mounts

Solenoid attachment to

cart

• Solenoid specification shows desired mounting to be at ends of magnet. • Details will need to be worked out with Vendor• CTOF will be mounted from both ends• Central Tracking Detectors must be mounted from upstream end only or we will

loose HTCC and CLAS12 acceptance



High Threshold Cerenkov Counter

• HTCC surrounds the solenoid and CD from outside

• It also protrudes inside with close clearance to the CTOF and also FST or other central tracker

• Several Moeller Electron Shields are planned

• They are envisioned to be cantilevered off the Torus

• Materials to be Lead or Tungsten or a combination

• Different configurations depending on the type of run (rastered or normal beam)

High Threshold Cerenkov Outer cone- very close to

light guides



Central Detector Section View

• CTOF – ID = 500mm– OD = 563 mm

• HTCC starts at 380mm (desired to start earlier)

• Moeller Shield fits very closely to inside cone of HTCC

High Threshold Cerenkov Outer cone- very close to

light guides

Moeller Shield



Solenoid and Central Tracker

• SVT/Central Tracker supported off the Solenoid upstream Flange

• 6 link support system is the current design



Latest Central Tracker Layout

• Two size BST stave assemblies

• Target size limited to 3” OD

• Considering removable R1 BST to allow HD Ice target

• Max radius of Central Tracker 238mm

• Note the HTCC starts at 380 mm so there is some room for Micro Megas



Silicon Vertex Tracker

Cold plate with brass inserts

Stave support

Stave

• Cooling analysis shows efficient heat removal• Deflection analysis complete • Assembly and alignment methods will be

confirmed with region 1 barrel assembly• Documentation and tech notes at

http://clasweb.jlab.org/wiki/index.php/CLAS12_SVT

http://clasweb.jlab.org/wiki/index.php/CLAS12_SVT



Latest Stave Design

Copper/Aluminum Nitride

FR4

Silicon 3 places

FR4

Copper

Rohacell

• Many designs considered• Latest design uses Silicon Wafer as

structure as well as detector, (proposed by M. Merkin and analyzed by S. Mandal)

• Prototype cores formed at JLab in mold• First results give core thickness 2.78mm

+/- 0.015mm, with higher quality mold we expect better



SVT Engineering Results Item Units ValueCoolant temperature

C 15

Peak temperature C 22.1Maximum deflection

Microns 10 fixed-pinned (R3&4)

R2 BST thermal analysis

Max. Deflection ~10.5m

R3&R4 BST deflection analysisMax. Temp ~22.1 C



CTOF

• There have been two parallel design efforts• One with standard PMT’s and one with high magnetic field

PMT’s decision on which one is pending more study on HF PMT design



Solenoid and CTOF

• CTOF is supported from both the upstream and downstream flanges of the solenoid

• Room for Central calorimeter or Neutron detector is being left for future upgrade



Installation of Counter Assembly

• Reference (conservative) design shown here

• Counters will be built and tested complete

– Light guides glued to scintillator– Wrapped and light sealed– PMT’s and 2 of the 3 layers of shield

pre-installed• Individual counter assemblies will be

installed one at a time• A strong-back will support the

counters to prevent bending and glue joint failure

• Installation fixture will clock the light guide assembly to the proper Φ angle

Counter exploded view

Strong Back



Counter Assembly Installed

• Installation fixture will roll counter assembly into position through the Solenoid bore

• Light guide assembly will be mounted to permanent clamps, then strong-back clamps can be removed



Beam Line• Most Beam Line Devices reused from CLAS

– Steering , focusing and raster magnets– Beam Profile Monitors and Beam Position Monitors– Cryogenic Target– Photon Devices will be left on beam line including Photon Tagger, radiators,

collimators and pair spectrometer• Shielding after target simulated and defined through the Torus• Re-arrangement of Moeller measurement system components, a

study optimizing this is underway Shielding

Cryogenic Target and

Cart

BPM’s (2)

Raster Magnets (2 pairs)

Tagger Magnet and other

Photon Devices



Hall B Prepared for CLAS12 Installation

Forward Carriage with

Electromagnetic Calorimeters

Space Frame Cleared of Beam Line equipment



CLAS12 installation schedule



CD installation

• An additional level will be added to the space frame for the CD and HTCC

• Torus will be installed next

• The Solenoid will be craned in

• CTOF will be installed after solenoid acceptance testing

• Central Tracker is installed last



Torus Assembled and Central Detector added

Solenoid and Central Detector - slides on rails into the space

frame for maintenance

Torus positioned and

alignedSpace frame

addition for Central Detector and HTCC



Safety• To work in Hall B all persons must be Trained and Qualified

• All work in Hall B work is scheduled and reviewed by the Hall Work Coordinator

• Independent activities have been and will continue to be reviewed for space and resource interferences

• Stop Work Program will always apply

• ISM principles must be followed

• Lock Tag and Try/LOTO will be used

• Tested and Inspected lifting fixtures

• PPE will be worn as required

• Hall B is a low radiation environment this will allow most items to be removed from the hall after survey w/o delay.



Summary

• Design of CTOF and SVT proceeding

• Will be working with Solenoid vendor on supports for CD

• Looking forward to contributions on Central Detector

• Planning for installation being integrated in the design phase



CLAS12 is COMPLETE!

Documents

CLAS12 Central Detector Overview and Integration