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Progress of polarized HD target

Progress of polarized HD target. HD group LEPS RCNP C. Morisaki. ・ contents. ① Development of NMR measurement system for the polarized HD target ② Development of s ingle crystal HD target. ① NMR T. Kunimatsu (RCNP) K. Fukuda (Kyoto univ .) (C. Morisaki).

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Progress of polarized HD target

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  1. Progress of polarized HD target HD group LEPS RCNP C. Morisaki

  2. ・ contents ① Development of NMR measurement system for the polarized HD target ② Development ofsingle crystal HD target

  3. ① NMR T. Kunimatsu (RCNP) K. Fukuda (Kyoto univ.) (C. Morisaki) • In the case of proton in HD, ～95% of polarization will be expected at 17 Tesla and 10mK. How to measure ? “ the NMR method ”

  4. ・ A first step of NMR • Check the NMR spectra of LH2 with use an one of the NMR system, called “single coil method”.

  5. ・ single coil method ・ Single coil method uses one coil takes both transmitter and receiver coil. ・ Cancellation circuit for keeping away signals which enter in Lock-in Amp at direct without entering in the coil. signal ∝exp(iθ)

  6. cylindrical sample cell (Stycact) NMR coil covers the whole region The H2 consisted in the cell was liquefied at 17K. The magnetic field was swept from 0.405T to 0.41T. The signal frequency was fixed 17MHz.

  7. Im part • Spectra of LH2with single coil method ※Resonance frequency of H2 is about 17MHz at field of 0.407Tesla. Re part magnitude of signal (V) 0.405 0.407 0.41 magnetic field (T)

  8. The longitudinal relaxation timeＴ１of NMR is related to the intensity of the signal and thetransverse relaxation time Ｔ２is related to the line width. T1 : It is time from after stop a 90°pulse to system backs a equilibrium to vertical. apply 90°pulse and stop T2 : It is time from after stop a 90°pulse to system backs a equilibrium to horizontal. apply 90°pulse and stop

  9. Polarization P depends on exp(-t/T1) . t：time Signal depends on dP/dt = (-１/T1)・ exp(-t/T1) . The shorter T1 is, the higher peak becomes. The polarization will be obtained by integration of the peak. At these points, We can think that 2 peaks are consisted by 2 sorts of Hydrogen-state which take a difference state respectively.

  10. Comparison between spectra of LH2 and non-LH2 That is ・・・ →The sharp peak came from LH2 . { T1:short →Hydrogenincluded in Stycast brought about the broad peak. { T1:long LH2 in a cell empty cell (Stycast) ← background

  11. ・ Summary of NMR • Make a new cell made of non-Hydrogen material in order to exclude the background. exam) Kel-F • Change the NMR system from single coil to crossed coil method has a high accuracy. • Calculate the polarization by integration of a peak area after excluding the background. single crossed crossed LH2 → LH2 → HD Stycast Kel-F Kel-F

  12. ・ crossed coil method ・ Coils lie orthogonally each other. → There is no influence from magnetic field made by signals each other. ・ Coils are separated each other. → It is not necessary to use a cancel circuit.

  13. ② Single Crystal (SC)M. Utsuro (RCNP) T. Kuwai (Toyama univ.) T. Ohta (RCNP) at inner of dilution refrigerator (DR) a few ten mK below 10mK 6mＫ 6mＫ low thermal conductivity → ～10 W/K・m high thermal conductivity → about ～103 W/K・m But ・・・

  14. These aluminum wires will bring the background at LEPS experiments. ( Of course, there is few problem at LEPS experiments, if we take a difference between a date of HD which include the aluminum and a date of only aluminum.) high thermal conductivity without aluminum wires “ Single Crystal -HD target”

  15. ・ What is the Single Crystal ? • Single Crystal is a crystal which has hexagonal close-packed structure. ・ Normal crystal ・ Single Crystal = HD low density　→　 low thermal conductivity high density　→ high thermal conductivity

  16. ・ A making method of SC • Normal crystallization ① only cool down from 300K to 10mK • Single crystal 　① cool down to around 10K which is temperature that the HD starts crystallization ② make a difference of temperature in between a bottom of the cell and a top of the cell to use heaters, cool down at a fair low speed, insert the HD in the cell slowly, crystallize the HD from the bottom of the cell

  17. ・ A first step of SC development at lab of the University of Toyama. • A conductivity measurement on SC-HD was undertaken with LHe cryostat.

  18. After crystallization, the conductivity measurement was carried out. result This is the world first report on thermal conductivity of the single crystal HD. Heat flow // z-axis

  19. ・ Summary of single crystal • The improved measurement will be performed soon. The conductivity will be further enhanced with (ⅰ)higher HD purity (>99.9%) prepare with a distillation apparatus to reduce the impurity contribution; by about 100 times, and (ⅱ) heat flow perpendicular to the z-axis of the single crystal; by about 50 times.

  20. Fin

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