Polarized Target “Issues”

MagnetMicrowaves

Target Ammonia

UVA/SLAC/JLAB Target

SMCryostat_95.ps

Magnet

• After SANE, and operation over 20 years in sometimes extreme conditions, magnet returned to Oxford Instruments for retuning.

• Diagnosis was that magnet had become unstable over the years because of relaxation of the clamping of the coils.

• At Oxford Instr. Coils reclamped to original specifications.

• Magnet retested:• 1) Ramped at higher than original specified rate to 5.1 T Quenched after 15 mins in persistent mode ( training quench)

• 2) Ramped at specified rate to 5.0 T Stayed at field in persistent mode for 105 minutes before ramping down• 3) Ramped to 5.1 T at same rate as Test 1 Stayed at field for 105 minutes in persistent mode before ramping down.

Ready to operate again in extreme conditions.

Microwaves

• 140 GHz/5 T EIO – have several NH3 Polarization > 90%• 70 GHz/2.5 T Carcinotron (have several) or EIO (borrow one from Duke University). EIO has

higher power output than Carcinotron. Polarization ~40% Changing EIOs easiest to do – use same power

supply.

Microwaves (contd.)

• Microwave guides at 70GHz. (Have at UVA)• Frequency and power read-outs at 70 GHz

(Have at UVA )• EIO power supplies ~ four, between UVA and

JLab• Carcinotron Power supplies: one at UVA, one

somewhere in Germany on way to UVA

NMR

• Have all the necessary equipment, many Q –meters, several signal generators and power supplies.

• Only need to retune system at 106.5 MHz (2.5 T) from 213 MHz (5 T)

Ammonia Targets

• All the polarized material will be irradiated ammonia (14NH3).

Ammonia Targets (contd.)

• Ammonia irradiated at the MIRF facility at NIST

• Use 19 MeV electrons at 10 – 15 μA• Irradiate to the level of ~1017 e-.cm-2 One irrad. Load ~ 2.5 target loads• Need ~ 18 target loads

Ammonia Targets (contd.)

• Current inventory: ~ 16 target loads – checking further.

• Unirradiated inventory: 3 target loads – checking further

• Previously used material: ????• Next irradiation (probably June)• Last Irradiation: October 2009

NH3 (2nd Batch)

Participation

• Faculty Level Don Crabb, Donal Day, Oscar Rondon• Post Docs Hovannes Baghdasaryan, Narbe Kalantarians Jonathan Mulholland?• Students• “Stache” Kvaltine, Zihong Ji, Mikhail Yurov