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 targetPolarization MethodHD 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 disadvantageHD molecule does not contain heavy nuclei such as Carbon and Nitrogen. Good for experiments observing reactions with small cross sectionThe HD target needs thin aluminum wires (at most 20% in weight) to insure the cooling.

Polarization H : 90 % D : 60 %

Relaxation Time30 days at 200 mK and 1 T during the experiment.

Target Size25 mm in diameter 50 mm in thickness

HD target transportationRCNP Osaka university

From RCNP to SPring-8

BL33LEP SPring-8

K+

K-

In Beam Cryostat

Transfer Cryostat 1

Transfer Cryostat 2Experiment

HD Target

Dilution Refrigerator

StorageCryostat

Dilution refrigeratorLeiden 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 RCNPLeft : used at SPring-8

SC（ Storage Cryostat ）

LN2 bath

LHe bath

main bath

outer vacuum chamber (OVC)

target

superconducting magnet

Al wire

2.5cm

IBC （ In Beam Cryostat ） for BL33LEP

TC leak test by He detector

He detector

Step0: turn to “0”, then wait until “P” saturate

closed

3

0

1

2

4

5OPEN

P

D

outside

Step1: turn to “1”, then wait until “P” zero

closed

3

0

1

2

4

5OPEN

P

D

outside

Step2: turn to “2”, then wait until green LED light

closed

3

0

1

2

4

5OPEN

P

D

outside

Step3: open “3”

opening

3

0

1

2

4

5OPEN

P

D

outside

Step4: turn “to 4”,if “P” increase now, the pipe is broken

then wait until “D” zero

opened

3

0

1

2

4

5OPEN

P

D

outside

Step5: turn on “5”,adjust the unit of concentrationstart measurement (see “D”)

opened

3

0

1

2

4

5OPEN

P

D

outside

purify HD

purify HD

Distillator

topD2 solid, H2 gas, HD liquid

middleD2 solid, H2 gas, HD gas

bottomD2 solid, H2 gas, HD gas

HD～ 96％

D2～ 2％

H2～ 2％

H2～ 50％

HD～ 50％

2 week

H2

H2～ 4~6％

HD~95%

2 week

HD～ 99.999％

principle of concentration sensor

• use filament to ionize gas

ionize gas here

H2+

D2+

HD+

sensor

digital data

AMP(amplifier)

In amplifier, use different gain for each gasPC

SC（ Storage Cryostat ）

cooling system test

SC（ Storage Cryostat ）

LN2 bath

LHe bath

main bath

outer vacuum chamber (OVC)

target

superconducting magnet

four thermometers in SC

Step 1

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.

SC（ Storage Cryostat ）

superconducting magnet test

Hall probe magnet sensor

1. Electrons (not Conventional current!) 2. Hall element, or Hall sensor3. Magnets 4. Magnetic field 5. Power source

We installed a Hall probe into main bath in SC.

superconducting magnet1. Zero the current. 2. Increase current, reach to middle current we set before ,then reach to max current we set b

efore (Heater on）3. Turn off Heater when reach the magnetic field intensity we need.4. Decrease the current to middle current we set before, then zero the current.5. Keep the persistent mode when we use superconducting magnet.6. Increase current, reach to middle current we set before ,then reach to max current we set b

efore (Heater off）7. Heater on (Quenches) (dangerous!!)8. Decrease the current to middle current we set before, then zero the current.9. 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 oth

erwise 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 on15:38

Heater off15:53

Heater on16:21

persistent mode28Mins

Amps

mV

Heater on16:30

Bonus

Physics objectives1 To investigate the ss content in the nucleon by the p -> p (n -> n) reaction To know the structure of the proton and neutron correctly is the

fundamental desire.

2 To determine the spin-parity of + 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.

concentration

sensor

pressure controller

pressuremonitorDistillator

top

middlebottom

throw gas out

concentration measurement

A

B

C

D

E

F

G

H I

1. open A, get gas for top of Distillator. J

2. close D, open B, then close B, now gas in C. 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

6. close the software RGA

gas here

gas here

gas here

gas here

0. A ,B should closed, open D and G, measure background.

5. measure gas concentration by RGA (Residual gas Analyzer)

7. open G, then close G throw the gas away

gas outside

gas here