HD target Grass 2008/09/03
Outline • Why we need polarized target. • Why we choose HD • HD target overview • Polarization method of HD target • NMR signal test • The first HD NMR signal in DRS • In the future
Yukawa coupling t We can change the meson and baryon meson baryon
We can not have this reaction Rest P Momentum conservation Impossible!!!! Energy conservation
Uncertainty principle Δl We can get it , if just in very short time, very short distance.
Of course, we also have this. But, it is more subtle!! At this moment, we have one proton and one pion!!! It maybe implied the existence of penta-quark.
The γp→φp reaction OZI Diffractive production within the vector-meson-dominance model through Pomeron exchange One-pion-exchange uud-knockout ss-knockout A.I.Titov et al. Phys. Rev. C58 (1998) 2429
Cross section Vector-meson-dominance model Cross Section at Eg = 2.0 GeV One pion exchange ss knockout Pomeron exchange is more ten times than anothers Only the Pomeron exchange is clear. uud knockout A.I.Titov et al. Phys. Rev. C58 (1998) 2429
Beam target asymmetrymore sensitive to understand the components of cross section Cancel the systematic error example P A
How can ss content be measured S=+1 S=+1 S=+2 S=0 S=+1 S=-1 S=-1/2 S=+1/2 S=-1/2 S=+1/2 S=+1 S=+1 S=+1 S=+1 Cancel Cancel S=0 S=0 S=+1/2 S=-1/2 S=+1/2 S=-1/2 sp: polarization of proton is parallel with polarization of target sA: polarization of proton is anti-parallel with polarization of target
LEPS, Spring-8 (calculated by A.I. Titov) with 1% ss-bar content Theory Beam-Target double spin asymmetry at Eg = 2.0 GeV Strangeness content is assumed to be 0%(Solid), 0.25%(Dashed), and 1%(Dot-dashed). (h0,h1) is the relative phase between the strange and non-strange amplitudes. A.I.Titov et al. Phys. Rev. C58 (1998) 2429
What the real compose? K+=493 Λ=1115φ K++ Λ=1608 p=940 φ =1020 p+ φ=1960 Maybe we will get different result with Titov.
Why we choose HD Symmetry requirement polarization is low H2 HD D2 H H H D D D 18.6 days 6.3 days Polarized this hetero-HD (boson “D” and fermion “H”) no Symmetry requirement
HD target overview Purify HD Transport of polarized target
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 300 mK and 1 T during the experiment. Target Size 25 mm in diameter 50 mm in thickness
Transport of polarized HD target @Osaka Uni. RCNP ④ ① ⑤ ② ⑥ ③ 蒸留器
top D2 solid, H2 gas, HD liquid middle D2 solid, H2 gas, HD gas bottom D2 solid, H2 gas, HD gas
H2～50％ H2～2％ HD HD～50％ HD～96％ Extraction Extraction HD～99.999％ H2 HD HD D2～2％ D2 D2 H2 2 week 2 week H2～4~6％ HD~95%
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
No.2 Dilution refrigerator Leiden Cryogenics BV DRS-3000(He3-He4) Cooling power3000μW at 120mK Lowest temperature~6mK
No.3 １７Tesla Magnet • Magnetic Field 17T at 272.15A • Homogeneity of Magnetic Field5×10-4 for 15 cm • Size&Bore diameter 1772×φ72.4
No.4TC（Transfer Cryostat） TC 1 Storage Cryostat IBC TC 2 Dilution Refrigerator HD Target 4He cryostat Magnetic Field : ~0.1 Tesla Right : used at RCNP Left : used at SPring-8 HD building SPring-8 Experiment K+ g K-
No.5SC（Storage Cryostat） Cryostat for Transportationfor Spring-8. The absorber place around cryostat Lowest temperature 1.5K with He4 pumping LHe consumption?L / day Magnetization 2.5T at 37.4A
No.6 IBC（In Beam Cryostat） 2.5cm Al wire
N- B N+ Boltzmann law of statistical mechanics | -1/2> DE=gmNB |+1/2>
| -1/2> DE=gmNB B |+1/2> Boltzmann law of statistical mechanics Symmetry requirement hetero-HD (boson “D” and fermion “H”) no Symmetry requirement S. Bouchigny, et al., Nucl. Instr. and Meth. A 544 (2005) 417.
Why choose “static methods” • Dynamic Nuclear Polarization Doping unpaired electron on the material. Spin is transferred from unpaired electron by laser-ray. Merit: Degree of polarization is very high. Demerit: Include extraneous material Portion H = 10/74 (C12H10) portion D = 20/84 (C12H10) • Spin exchange with alkaline Doping alkaline like a Rb on the material. At first, alkaline is polarized by laser. Spin is transferred from polarize alkaline to the material by spin-spin interaction. Merit: No special Demerit: Include extraneous material Portion H > 5 ? Portion D <5? • Static method(HD) Polarizing with strong magnetic field and low temperature. And doeped ortho-H2 as a catalyst for acceralate spin exchange Merit: Degree of polarization is very high. Not include extraneous material Demerit: The cost is very high! Duration of life is long. Potion H = 1/3 (HD) Portion D = 2/3 (HD)
・ single coil method 4 1 2 3 ・ Cancellation circuit for keeping away signals which enter in Lock-in Amp at direct without entering in the coil. ・ Single coil method uses one coil takes both transmitter and receiver coil. 5
Cancellation circuit 1 We cancel the special frequency only 14MHz 15MHz 16MHz
Single coil 5 We use plastics coil base which made by stycast chemical compound with H
The longitudinal relaxation time T1 of NMR is related to theintensity of the signal. • The transverse relaxation time T2 is related to the line width. sharp peak comes from liquid H2 broad peak is due to the proton in Stycast liquid H2 :long T2 ; Stycast :short T2; short T1
NMR signal test by liquid H2 We don’t got enough data point. We changed the multimeter to high speed one after this test
NMR coil made by Kel-F Cell with Al wire
Prototype 1 • [HD]~ 99% • N=1.2mol • T=14.5mK • B=17T • During 33 Days PH~83% PD~24%
purpose • Make sure the NMR method can be used in DRS • Get some H signals • Second purpose, get the D signals
Step and result • Decrease the magnetic field : 17T→ 1T • Sweep region: 1T±0.2T • Sweep speed: 300A/1000min (5mA/s) (3.12Gauss/s) • RF field frequency fixed in 46.925MHz • We get H signal around 1.17T. • Use the same condition get several signals.
We got a small signal near H, that is 19F signal, come from the Kel-F (plastics coil base) The D signal should be around 7.3T, we sweep the region (7.3T±1T), but we can not find it . Step and result
The different sweep direction, will got different magnetic field 18.8A→19.2A 19.2A→18.8A it due to hysteresis between power supply and superconductor coil Discussion- B field • We estimate the magnetic field by the current of superconductor. • We estimate the current by the voltage of superconductor. • The relation between magnetic field and voltage maybe not exact linear. • We should consider more conditions to reduce the error. Maybe we can put teslameter. (ex:Hall probe)
The polarization is proportional to the integrated area S of the NMR signal. This is our first NMR measurement. It is difficult to judge that the accuracy is good or not. Discussion- polarization S Nagoya University, Kondo, PHD thesis,P61
Discussion-D signal • We got the clear H signal. • Sensitivity of NMR D signal is 1/100 of H signal, and the polarization of D is 1/3 of H, the D signal is 1/300 of H signal. • We can sum hundred signals to get D signal. But NMR measurement will broken polarization. • Sweep the B field also will change the condition of polarization. (D resonance ) • In order to get good H signal, we will skip D signal and focus on H signal this time.
Simulate IBC condition • IBC is where we want to use polarized target. • We want to know polarization status in IBC condition. • B~1T • T~300mK • Due to long relaxation time ,even we increase the temperature from 15mK to 300mK, the polarization of HD should keep. (We hope the relaxation time is one year.)
But when we just reached 300mk NMR signal decreased. P300mk≈67% * P14.5mk -0.0000234986 -0.0000156769