HD target

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 From RCNP to SPring-8 BL33LEP SPring-8  K+K+ K-K- In Beam Cryostat Transfer Cryostat 1 Transfer Cryostat 2 Experiment HD Target Dilution Refrigerator Storage Cryostat

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

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

NEXT Develop NMR system To advance the dilution refrigeration pure HD gas To advance the connector from target to cooling system

Temperature calculation of HD target

Temperature calculation of HD target by M. M. Lowry. M M Lowry, F Lincoln, L Miceli, T Saitoh, A Sandorfi, X Wei, C Whisnant. Progress on the LEGS polarized HD target. Int'l workshop on polarized beams and polarized targets, PST 2001, Vol Sept 2001, (2001)

Thermal conductivity of Aluminum （ W/k-m ） Q= heat flow rate = 0.5 μW ΔT = temperature difference =T 2 -T 1 L = the length of aluminum wire = 5 cm A = (section area of one aluminum wire) × (number of aluminum wire) = × (Diameter of wire) 2 × (Number of wire) L Area Q T1T1 T2T2 Al

Aluminum wire temperature We cut the aluminum wire to N part κ (figure) = κ Al / T Al κ Al = κ (figure) × T Al ΔL = (the length of aluminum wire ) /N T1T1 Al ΔLΔL T0T0 TNTN T2T2...

T of wire at ring 17 mk T of wire at top of HD mk T of wire at middle of HD mk 2.5cm T of wire at end of HD mk 2.5cm 3cm Q = Ortho Decay Heating = 0.5 μW Wire material= Al 5056 Number of wire = 3000 Diameter of wire = 38.1 μm Thermal conductivity of Al wire= 0.7 W/m/K^2 T of wire at ring17 mk T of wire at top of HD mk T of wire at middle of HD mk 2.5cm T of wire at end of HD mk 2.5cm 3cm Q = Ortho Decay Heating = 0.5 μW Wire material= % Al Number of wire = 2000 Diameterof wire = 50.8 μm Thermal conductivity of Al wire= 600 W/m/K^2 T of wire at middle of HD

HD temperature next to aluminum wire Kapitza resistance = Thermal boundary resistance =Contact resistance

HD temperature next to aluminum wire Q (A. Honig) = heat flow rate = 2.8 ×10 -8 (W) D wire (A. Honig) = diameter of wire = 50 μ m N wire (A. Honig) = number of wire = 60 L wire (A. Honig) = length of wire = 5 cm A surface (A. Honig) = (surface area of one aluminum wire) * N wire = π × (Diameter of wire) × ( Length of wire ) × ( Number of wire ) = π × ( ) × (0.05) × (60) (m^2) = (m^2) A. Honig, Q. Fan,X Wei, A. M. Sandorfi, C. S. Whisnant, Nuclear Instruments and Methods in Physics Research Section A (1995)

HD temperature next to aluminum wire The Kapitza resistance is (W/ (m^2) (mk^3)). The error of kapitza resistance is (W/ (m^2) (mk^3)) Q = Ortho Decay Heating = 0.5 μW Wire material= % Al Number of wire = 2000 Diameter of wire = 50.8 μm Length of wire= 5 cm TAl= mk Asurface = π × (Diameter of wire) × (Length of wire) × (Number of wire) =π × ( ) × (0.05) × (2000) (m^2) = (m^2) THD= = (mk) = ± (mk) T of wire at middle of HD

thermal conductivity of HD Where α, β, γ, δ, σ are constants, which given by REF3, α=0.099, β=1.32×10-3, γ= 0.57, δ=0.0031, σ=3.34 ×10-3 Where “T” is the temperature of HD. Where “c” is the (J=1) concentration. J = rotational quantum number o-H2 (J=1) p-H2 (J=0) time → ∞, c→ 0

HD temperature farthest to aluminum wire J. H. Constable and J. R. Gaines, Phys. Rev. B 8,3966 (1973)

Al riri roro HD q HD temperature farthest to aluminum wire this boundary conditions T = Ti at r = ri T = Toat r = ro

HD temperature farthest to aluminum wire...

Use computer to calculate temperature Al % Al Numer of wire L5 cm r section radius of HD target 1.25 cm r0r μ m25.4 μ m r N (r effective section radius per wire) μ m μ m T0T mk19.84 mk T N in figure mk19.94mk T N in our calculation133.8 mk mk

Calculation of various HD target T of wire at ring 17 mk T of wire at top of HD mk T of wire at middle of HD mk 2.5cm T of wire at end of HD mk 2.5cm 3cm Q = Ortho Decay Heating = 0.5 μW Wire material= % Al Number of wire = 2000 Diameterof wire = 50.8 μm Thermal conductivity of Al wire= 600 W/m/K^2 Volume ratio ( Al /(HD+Al))= T of HD next to HD ± mk T of HD farthest of wire mk

Q (μW)0.5 Wire material % Al Length of Wire (cm)5 T of wire at ring (mk) 17 Number of wire Diameter of wire (μm) Volume ratio ( Al / HD+Al) T of wire at top of HD (mk) T of wire at middle of HD (mk) T of wire at end of HD (mk) T of HD next to HD (mk) ± ± ± ± ± ± ± ± T of HD farthest of wire (mk) Number of wire Diameter of wire (μm) Volume ratio ( Al / HD+Al) T of wire at top of HD (mk) T of wire at middle of HD (mk) T of wire at end of HD (mk) T of HD next to HD (mk) ± ± ± ± ± ± ± ± T of HD farthest of wire (mk)

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 ～ 96 ％ D2～2％D2～2％ H2～2％H2～2％ H 2 ～ 50 ％ HD ～ 50 ％ 2 week H2H2 H 2 ～ 4~6 ％ HD~95% 2 week HD ～ ％

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

concentratio n sensor pressure controller pressure monitor Distillator top middle bottom throw gas out

concentration measurement A B C D E F G HI 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 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

Physics objectives 1To 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. 2To 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.