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1、projector test,APS-DNP 2019 Session DA:Probing the Gluonic and Quark Structure of Matter,DA1.First Experiments with a Polarized Hydrogen Jet Target in RHIC,Willy Haeberli Department of Physics,University of Wisconsin-Madison,DA Probing the Gluonic and Quark Structure of Matter,Measuring the Polariza
2、tion of High-Energy Protons WHY?HOW?,K.Rith DIS 2019,DIS of polarized HE leptons(e,m)from polarized nucleons atSLAC,CERN,HERA:,Good agreement with two very different experimental methods.,What accounts for the spin of the nucleon?,The(old)proton spin puzzle:Only(204)%of proton spinisaccounted for by
3、 spins ofquarks and antiquarks,COMPASS polarized LiD target,E=160 GeV,pB-76%1.8*107/sec(time ave)polarized LiD-target,pT 50%Luminosity:5*1032 cm-2 s-1,Polarization:50%Dilution 40%,HERMES internal target,Factor 100 gain fromuse of“storage cell”(S.Price),Polarized H,D injection,To H,D polarimeter,.,Pu
4、re polarised gas targets:H,D,target polarisation:pT 85%target thickness 1014 H/cm2Luminosity:6*1033 cm-2 s-1(D 50 mA)spin reversal every 120 sec,0.1 Gluon?Orbital?,Gluons:key contributor to the proton spin?,slide adapted fromW.Vogelsang(BNL),Gluons:Measurements of DG/G,from F.H.Heinsius,COMPASS Coll
5、ab-DIS April 2019,PHENIX and STAR at RHIC will measure DG by collisions of longitudinally polarized HE protons-ALLRHIC:c.m.energies up to 500 GeV,RHIC experiments will measure DG,BUT HOW DOES ONE KNOW Pbeam?,Colliding polarized protons couple directly to gluons(rather than via charge)-measure parton
6、 asymmetries.Measure polarization of gluons through g,jets,p pis,heavy quarks.,G.Bunce DUBNA-SPIN-03,The RHIC Complex 50 s 500 GeV,STAR,PHENIX,Spin Rotators,20%Snake,PHOBOS,SiberianSnakes,present performance:L=4x1030s-1cm-2,Pbeam 40%,5%Snake,0.7 1011 pol.protons/bunch56 bunches,RHIC,What mechanism i
7、s sensitive to P at high energy?Need to know analyzing power A.,Measuring polarization of proton beam,Reverse P to eliminate instrumental asymmetry,Magnetic Moment Scattering,Mott(1929),J.Schwinger(Phys.Rev.73,1948),Analyzing power in small-angle neutron scattering.,“It is the purpose of this note t
8、o suggest a second mechanism for polarizing fast neutrons-the spin-orbit interaction arising form the motion of the neutron magnetic moment in the in the nuclear Coulomb field.”,Spin-orbit coupling:,Coulomb-nuclear interference(“CNI”),Phil.Mag.1,175(1956),10,10%,s,P,U(n,n)U100 MeV,FNAL E704 200 GeV/
9、cPhys.Rev.D48,3026(1993),AN vs momentum transferPolarized protons from Hyperon decay(low rate),CNI Analyzing Power in High-Energy pp Scattering,E950BNLp=21.7 GeV/cPhys.Rev.Lett.89(2019),with hadronicspin-flip,no hadronicspin-flip,momentum transfer(GeV/c)2,CNI Analyzing Power p-Carbon Scattering,cali
10、bration only at 22 GeV/csmall ANScale uncertainty 30%Unknown energy dependenceBut large count rates,need for accurate absolute AN measurement,Beam Polarization Calibration,Measure asymmetry etgt when unpolarized beam is scattered from polarized target of KNOWN polarization Pt-measures A,Measure asym
11、metry ebeam when polarized beam is scattered from unpolarized target,Elastic scattering of IDENTICAL particles(pp):beam analyzing power=target analyzing power(Change in reference frame),Both experiments done simultaneously,The Polarized Target-Principle,acceptance angle a,.and Practice,Cooled dissoc
12、iator nozzle to reduce v and v-spread.recombination:dissociation depends on gas flow and nozzle temp Beam attenuation:rest gas and intrabeam scattering Magnet design(taper,lengths,z-position)needs:velocity distribution,dissociator H output vs gas flow,nozzle T beam forming geometry differential pump
13、ingOPTIMIZATION:COMPUTER MODELLING,rare-earth perm.magnets,pole tip 1.5T,max d|B|/dr=6T/cm),overall design:Tom Wise,UW,24 sectors separatingmagnets with 1.5 T field at the pole tips.,H-jet sextupole separation magnet system.,0 0.5m 1m 1.5m,p-beam,separationmagnets(sextupoles),H2 dissociator,Polarime
14、ter,focusingmagnets(sextupoles),RF transitions,holding fieldmagnet 1.2 kG,recoil ChamberSilicon Det.,(1),(2),Pz+:(1),(4)(transition(2)(4)Pz-:(2),(3)(tranistion(1)(3),Hyperfine state(1),(2),(3),(4),The Polarized H-jet at RHIC,Beam intensity:(1.20.2)1017H/s,Nuclear polarization of H-atoms,Efficiency o
15、f RF transitions:(99.70.2)%ideal proton polarization for B=1.2kG:P=0.960 plus 3%dilution from H2 P=0.924 2%bunch-field depolarization 0.1%,Scattering Chamber(top view),H-jet profile,Target thickness:(1.3 0.2)x1012 H/cm2,Recoil detectors(blue beam):6 detectors 70 x64 mm 16 strips(5 mrad each)Measure
16、Energy:17MeV resolution 50 keV TOF:1680 ns resolution 2 ns Angle:10100 mrad(89.5-84O)resolution 5 mrad,Recoil Detectors,RHIC beam,Time of flight,CNI peak AN 1 E 2 MeV,Recoil protons elastic pp,0 1 2 3 4 5 MeV,Recoil energy vs.time-of-flight,0,sourcecalibration,Strip#,1,16,TR MeV,241Am,TOF+/-8 ns,TOF
17、 vs TR Si detector of first 8 channels,TR,TOF,analysis,Recoil energy strip by strip,241Am,Identifying recoil protons vs recoil angle(=strip#),pp Analyzing Power 100GeV/c,AN vs.momentum transfer,Polarization of 100 GeV Beam,study systematic errors and improve statistics for absolute calibration accur
18、acy 5%analyze wider t-range to study pp interaction bunch field depolarization with 110 bunches improved measurement of H2 contamination of H-beam measure beam polarization at injection measure blue and yellow beam polarization,Plans:,106 pp events,Wisconsin:,T.Wise,M.Chapman,W.H.BNL:A.Bravar,G.Bunc
19、e,R.Gill,Z.Li,A.Khodinov,A.Kponou,Y.Makdisi,W.Meng,A.Nass,S.Rescia,A.ZelenskiKyoto:H.Okada,N.SaitoITEP-Moscow:I.Alekseev,D.SviridaIUCF:E.StephensonRIKEN-BNL:O.Jinnouchi,Rikkyo U:K.KuritaANL:H.Spinka,H-Jet collaborators:,1.26 km,data to analyze,Recoil angle 89.5oRecoil energy 0.53 MeV 5.3MeV,pp Analy
20、zing Power 100GeV/c,AN vs.momentum transfer,Plans,Plans:improve statistics,study systematic errors for absolute calibration accuracy 5%analyze wider t-range to study pp interaction bunch field depolarization with 110 bunches improved measurement of H2 contamination of H-beam measure beam polarizatio
21、n at injection measure blue and yellow beam polarization,RHIC pp accelerator complex,BRAHMS&PP2PP(p),STAR(p),PHENIX(p),AGS,LINAC,BOOSTER,Pol.Proton Source500 mA,300 ms,Spin Rotators,Partial Siberian Snake,Siberian Snakes,200 MeV Polarimeter,AGS Internal Polarimeter,Rf Dipoles,p-C Polarimeters,Absolu
22、te Polarimeter(H jet),0.7 1011 pol.protons/bunch56 bunches,AGS pC Polarimeters,Strong AGS Snake,+-+-+-,+-+,L=4x1030s-1cm-2,Pbeam 40%,RHIC experiments will measure DG,BUT HOW DOES ONE KNOW Pbeam?,Colliding polarized protons couple directly to gluons(rather than via charge)-measure parton asymmetries.
23、Measure polarization of gluons through g,jets,p pis,heavy quarks.,G.Bunce DUBNA-SPIN-03,HERMES internal target,Pure polarised gas targets:H,D,target polarisation:pT 85%Luminosity:6*1033 cm-2 s-1(D 50 mA)spin reversal every 120 sec,Factor 100 gain fromuse of storage cell,The Data(a sample),number of
24、events(a.u.),ReconstructedMissing Mass2,FWHM 0.1 GeV2,SimulationMM2,FWHM 0.1 GeV2,Inelastic Threshold,GeV2,u+d+s 0,20 0,04.,QCD analysis of Q2 dependence:,K.Rith DIS 2019,DIS of polarized HE leptons frompolarized nucleons atSLAC,CERN,HERA:The(old)proton spin puzzle:Only 20%of proton spin isaccounted
25、 for by spins ofquarks and antiquarks,Two experimental methods:thick solid polarized target+low intensity e or m beam Thin polarized gas target+high intensity beam,What accounts for the spin of the nucleon?,preliminary,Non-hadron spin flip,(Re r5=-0.02),(Re r5=+0.02),Comparison with some models(Not
26、Fitting),Demonstrated feasibility of accurate beam polarization calibration at high energy calibration of p-C polarimeter measurement of pp AN(8 angles,10%)H-jet does not interfere with p-beam life time 3%measurement requires 200 hrs with improved beam intensity method covers entire energy range of
27、RHIC one important step towards a precise determination of DG,CONCLUSIONS:,Solenoidal field,Axial Field,STAR,RHIC experiments will measure DG,BUT HOW DOES ONE KNOW Pbeam?,PHENIX,Polarization of 100 GeV Beam,Plans:analyze wider t-range to study pp intercaction improve statistics bunch field depolariz
28、ation with 110 bunches improved measurement of H2 contamination of H-beam measure beam polarization at injection measure blue and yellow beam polarization,Eventual goal ofcalibration:3%,Forward scattering particle ID;Correlation of Energy and position,Strip#,1,16,TR MeV,241Am,TOF+/-8 ns,TOF vs TR Si
29、 detector of 16channels,#1,#16,#4,TR,TOF,analysis,H,The Polarized Target-Principle,H2,acceptance angle a,H,The Polarized Target-Principle,H2,acceptance angle a,Sextupoles:rare-earth permanent magnets(gradient up to 6 T/cm)Magnet geometry:2 magnet groups reduce chromatic aberrations magnet gaps reduc
30、e gas attenuation taper increases acceptance RF transitions of high efficiency very uniform guide field to avoid bunch field depolarization Field shaping for adiabatic transport responsible for design:T.Wise UW,H-Jet Design Features,permanent magnet sextupole pole tip field 1.5T,24 sectors separatin
31、gmagnets with 1.5 T field at the pole tips.,H-jet sextupole separation magnet system.,0 0.5m 1m 1.5m,p-beam,The Polarized Target-Principle,acceptance angle a,H,The Polarized Target-Principle,H2,acceptance angle a,acceptance angle a,Sextupoles:rare-earth permanent magnets(gradient up to 6 T/cm)Magnet
32、 geometry:2 magnet groups reduce chromatic aberrations magnet gaps reduce gas attenuation taper increases acceptance RF transitions of high efficiency very uniform guide field to avoid bunch field depolarization Field shaping for adiabatic transport responsible for design:T.Wise UW,H-Jet Design Features,谢谢你的阅读,知识就是财富丰富你的人生,
