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Instrumentation for PAX - Experiment at COSY

Instrumentation for PAX - Experiment at COSY. August 6, 2012 | Alexander Nass. COSY. Circumference : 183.4 m Injection energy : 45 MeV Maximal momentum : 3.65 GeV /c ( for p, d ) Electron cooling (100 keV ) up to 600 MeV /c Stochastic cooling above 1.5 GeV /c. PAX.

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Instrumentation for PAX - Experiment at COSY

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  1. Instrumentation for PAX - Experiment at COSY August 6, 2012 | Alexander Nass

  2. COSY Circumference: 183.4 m Injectionenergy: 45 MeV Maximal momentum: 3.65 GeV/c (for p, d) Electroncooling (100 keV) upto 600 MeV/c Stochasticcoolingabove 1.5 GeV/c PAX Formoreinformationabout PAX physicsseetalkof P. Lenisa GGSWBS‘12, Tbilisi, Georgia

  3. The polarizedtarget Productionof a polarizedatomic hydrogen beamby an ABS Increaseofthetargetdensitybymeansof a storagecell Analysis oftargetpolarizationby a BRP and TGA ABS BRP The polarizedtarget in thetestsetup GGSWBS‘12, Tbilisi, Georgia

  4. Hyperfine structureof hydrogen in groundstate Magnetic momentassociatedwithspin: In weakmagneticfield e- and p-spins coupletogethertoexternalfield (quantumnumber F, mF) In strong magneticfield e- and p-spins coupleseparatelytoexternalfield (quantumnumbers I, mI, S, mS)  S-orbital splitsinto 4 states GGSWBS‘12, Tbilisi, Georgia

  5. Hyperfine structureof hydrogen andpolarization Bc – criticalfield (BcH = 50.7mT) GGSWBS‘12, Tbilisi, Georgia

  6. Spin selectionwithsextupolemagnets GGSWBS‘12, Tbilisi, Georgia

  7. Spin selectionwithsextupolemagnets Hydrogen atomsofstate |1 in the ABS Cellentrance State |1  |3 in the ABS Sextupolmagnets GGSWBS‘12, Tbilisi, Georgia

  8. High frequencytransitions (HFT) Possibilityofexchangingtheoccupationnumbersofhyperfinelevels  changepolarization In experiment: RF immersedinto a staticmagneticfieldandappliedtoatomic beam Ifenergyof RF andstrengthofmagneticfieldmeetthecriterias exchangeofoccupation numbers MFT WFT SFT WFT - weakfieldtransition, MFT - medium fieldtr., SFT - strong fieldtr. GGSWBS‘12, Tbilisi, Georgia

  9. High frequencytransitions Probabilitythatatoms do notchangestate: GGSWBS‘12, Tbilisi, Georgia

  10. The atomic beam source DissociationofH2intoatoms in thedissociator Expansion ofthe gas intovacuumthroughnozzle, beam formationwithskimmerandcollimator (Electron) spinseparationandfocussingoftheatomsthroughsextupolemagnets Manipulation oftheoccupationnumbersandpolarizationusing high frequencytransitions Injectionofthepolarized beam intothestoragecell WFT 2-3 GGSWBS‘12, Tbilisi, Georgia

  11. The storagecellprinciple Storage cell - Increaseoftargetdensity due tomultiple passingoftheatomsthroughthetargetregion But: Suppression ofrecombinationanddepolarizationnecessary  useteflonfoilsorcoating Simple Jet–target: Polarizationasinjectedbythe ABS But: Low targetdensitybecauseeachparticlecrossesthetargetregiononlyonce GGSWBS‘12, Tbilisi, Georgia

  12. The (openable) storagecell PAX storagecellsincreasetarget gas densityuptoabout5 · 1013atoms/cm2 Openablecellnecessaryforstoredprotonbeamswhichhave large diameterbeforecooling (e.g. AD/CERN) PAX storagecellshaveABS tubeforinjectionoftarget gas andBRP tubetoextract a gas sample foranalysis in BRP GGSWBS‘12, Tbilisi, Georgia

  13. Densityofthepolarizedtarget gas in PAX Intensitymeasurementofthe ABSusing an absolute baratronpressuremeasurementin thecenter on thestoragecellin comparisonwith a calibratedfluxfrom an unpolarized gas feedsystem IH1 = (6.1±0.3)·1016 H/s In addition target thickness measurement using the beam energy loss method which is deduced from a shift of the orbit frequency of the coasting beam: d IH2 = (3.0±0.1)·1016 H2/s GGSWBS‘12, Tbilisi, Georgia

  14. Principleofpolarizationmeasurement Selection ofcertainhyperfinestateswithHFT‘sandsextupolemagnets Measurement ofintensityofthesestates in QMA WithknownefficienciesεofHFT‘s (fromcalibration) andtransitionprobabilitiesσofthesextupolemagnets - calculationofoccupationnumbersofhyperfinestates Occupation numbers: GGSWBS‘12, Tbilisi, Georgia

  15. Principleofpolarizationmeasurement Polarizationdepends on targetholdingfield Atlowfield (PAX): Target gas analyzerconsistsof QMA and beam chopper Measuresthe partial pressuresofatomsandmolecules in the effusive beam out ofthetargetcell Hydrogen atomic fraction: GGSWBS‘12, Tbilisi, Georgia

  16. Polarizationofthetarget gas in PAX Average target polarization: Atomic polarization: Polarizationinjectedintothestoragecell: Measuredpolarization in the BRP: Assuming the most probable, uniform distribution  GGSWBS‘12, Tbilisi, Georgia

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