HD target

outline HD target overview TC leak test by He detector purify HD SC（Storage Cryostat） cooling system test superconducting magnet test

HD target overview

Characteristics of polarized HD target Polarization Method HD target is polarized by the static method using “brute force” at low temperature (10 mK) and high magnetic field (17 T). It takes about 2-3 months to polarize the target. Advantage and disadvantage HD molecule does not contain heavy nuclei such as Carbon and Nitrogen. Good for experiments observing reactions with small cross section The HD target needs thin aluminum wires (at most 20% in weight) to insure the cooling. Polarization H : 90 % D : 60 % Relaxation Time 30 days at 200 mK and 1 T during the experiment. Target Size 25 mm in diameter 50 mm in thickness

HD target transportation RCNP Osaka university Transfer Cryostat 1 From RCNP to SPring-8 Storage Cryostat BL33LEP SPring-8 Experiment In Beam Cryostat Transfer Cryostat 2 Dilution Refrigerator K+ g HD Target K-

Dilution refrigerator Leiden Cryogenics DRS-3000　(He3-He4) Cooling power 　　 　 　　　3000μW at 120 mK Lowest temperature 　 　　　 6 mK Magnetic Field 　　　　 　　　17 T Homogeneity of Magnetic Field 　　　5×10-4 for 15 cm

Two Transfer Cryostats Right : used at RCNP Left : used at SPring-8

outer vacuum chamber (OVC) SC（Storage Cryostat） outer vacuum chamber (OVC) LN2 bath LHe bath main bath superconducting magnet target

IBC（In Beam Cryostat） for BL33LEP 2.5cm Al wire

TC leak test by He detector

He detector

Step0: turn to “0”, then wait until “P” saturate 3 1 2 4 5 OPEN P D closed outside

Step1: turn to “1”, then wait until “P” zero 3 1 2 4 5 OPEN P D closed outside

Step2: turn to “2”, then wait until green LED light 3 1 2 4 5 OPEN P D closed outside

Step3: open “3” 3 1 2 4 5 OPEN P D opening outside

Step4: turn “to 4”, if “P” increase now, the pipe is broken then wait until “D” zero 3 1 2 4 5 OPEN P D opened outside

Step5: turn on “5”, adjust the unit of concentration start measurement (see “D”) 3 1 2 4 5 OPEN P D opened outside

purify HD

purify HD

Distillator top D2 solid, H2 gas, HD liquid middle D2 solid, H2 gas, HD gas bottom D2 solid, H2 gas, HD gas

HD～99.999％ H2 H2～50％ H2～2％ 2 week 2 week HD～50％ HD～96％ H2～4~6％ HD~95% D2～2％

principle of concentration sensor use filament to ionize gas H2+ AMP (amplifier) sensor ionize gas here HD+ digital data D2+ In amplifier, use different gain for each gas PC

SC（Storage Cryostat） cooling system test

outer vacuum chamber (OVC) SC（Storage Cryostat） outer vacuum chamber (OVC) LN2 bath LHe bath main bath superconducting magnet target

four thermometers in SC

Step 1 Evacuate the OVC for at least 24 hour before pre-cool system

For pre-cool LHe bath, we fill LN2 to LHe bath. The Allen Bradly carbon resistance sensor in liquid helium bath reached 388.81 ohm. It is close to 77 K

Transfer the LN2 from LHe bath to LN2 bath. we fill LHe to LHe bath. The level of liquid nitrogen rose from 9.2% to 80%. The Allen Bradly carbon resistance sensor in liquid helium bath reached 2691 ohm (around 6~7 K)

Transfer the LN2 from LHe bath to LN2 bath. we fill LHe to LHe bath. We start pumping gas from main bath. The Allen Bradly carbon resistance sensor in liquid helium bath reached 4033 ohm (around 4~5 K) ,the temperature in bottom of main bath reached 3.096 K, the temperature in top of main bath reached 4.025 K. Temperature cannot drop more. The level of helium gas drop down. We find the helium tank empty.

pumping the main bath We remove the helium gas from main bath. The temperature in top of main bath rose from 3.441 K to 73.95 K. The temperature in bottom of main bath drop down from 2.983 K to 1.509 K . The temperature keep around 1.53 K.

Test of SC cooling system is finished.

superconducting magnet test SC（Storage Cryostat） superconducting magnet test

Hall probe magnet sensor Electrons (not Conventional current!) Hall element, or Hall sensor Magnets Magnetic field Power source

We installed a Hall probe into main bath in SC.

superconducting magnet Zero the current. Increase current, reach to middle current we set before ,then reach to max current we set before (Heater on） Turn off Heater when reach the magnetic field intensity we need. Decrease the current to middle current we set before, then zero the current. Keep the persistent mode when we use superconducting magnet. Increase current, reach to middle current we set before ,then reach to max current we set before (Heater off） Heater on (Quenches) (dangerous!!) turn off the heater. turn off the power supply. superconducting magnet test finish.

before we start test make the following electrical checks magnet resistance magnet to cryostat isolation switch heater resistance switch heater to cryostat isolation magnet to switch heater isolation (isolation values should typically be >1 MΩ unless otherwise stated) open all of doors in experiment building. take off everything with magnetic.

Typical calibration curve of Hall probe

The magnetic field of about 1 Tesla was confirmed by using a Hall probe. Heater on 16:21 Heater on 16:30 persistent mode 28Mins Heater off 15:53 Amps Heater on 15:38 mV

Bonus

Physics objectives To investigate the ss content in the nucleon by the gp -> fp (gn -> fn) reaction To know the structure of the proton and neutron correctly is the fundamental desire. To determine the spin-parity of Q+ particle Although I do not follow recent theoretical studies, to fix the initial nucleon spin and photon polarization must be important. 3 To study the reaction mechanism of the hyperon photoproduction Recently some interesting results measuring the double polarization observables appeared. Advanced studies need the polarized nucleon target.

pressure controller concentration sensor bottom middle top throw gas out pressure monitor Distillator

concentration measurement D B F A H I C gas here gas here gas here E gas here gas here 0. A ,B should closed, open D and G, measure background. 1. open A, get gas for top of Distillator. J G 2. close D, open B, then close B, now gas in C. gas outside 3. open D, then close D, now gas from C to E 4. control pressure by F, see J the pressure should be 9.0x10-7 mbar 5. measure gas concentration by RGA (Residual gas Analyzer) 6. close the software RGA 7. open G, then close G throw the gas away