简介:Thestudyofnucleonresonanceisanimportanttopicinhadronphysics.Themostimportantwaytostudythenucleonresonancesisthecollisionofthephotonandnucleon.Uptonow,theknowledgeaboutthenucleonresonancesaround2GeVisstillscarce.Recently,theCLASCollaborationatJeffersonNationalAcceleratorFacilityreleasedtheirexclusivephotoproductioncrosssectionsfortheΛ(1520),Σ0(1385)andΛ(1405)forenergiesfromnearthresholduptoacenterofmassenergyWof2.85GeVwithlargerangeoftheKproductionangle[1].SincethethresholdforthephotoproductionofΛ(1520)isabout2.01GeV,thenewexperimentaldatawithhighprecisionreleasedbytheCLASCollaborationprovideanopportunitytostudythenucleonresonancesabove2GeV.
简介:Wereviewthepresentstatusandfutureprospectsoffastignition(FI)researchofthetheoreticalgroupattheIAPCM(InstituteofAppliedPhysicsandComputationalMathematics,Beijing)asapartoftheinertialconfinementfusionproject.SincetheapprovaloftheFIprojectattheIAPCM,wehavedevotedoureffortstoimprovingtheintegratedcodesforFIanddesigningadvancedtargetstogetherwiththeexperimentalgroup.RecentFIexperiments[K.U.Aklietal.,Phys.Rev.E86,065402(2012)]showedthatthepetawattlaserbeamenergywasnotefficientlyconvertedintothecompressedcorebecauseofthebeamdivergenceofrelativisticelectronbeams.Thecouplingefficiencycanbeimprovedinthreeways:(1)usingacone–wire-in-shelladvancedtargettoenhancethetransportefficiency,(2)usingexternalmagneticfieldstocollimatefastelectrons,and(3)reducingtheprepulselevelofthepetawattlaserbeam.TheintegratedcodesforFI,namedICFI,includingaradiationhydrodynamiccode,aparticle-in-cell(PIC)simulationcode,andahybridfluid–PICcode,havebeendevelopedtodesignthisadvancedtargetattheIAPCM.TheShenguang-IIupgradedlaserfacilityhasbeenconstructedforFIresearch;itconsistsofeightbeams(intotal24kJ/3ω,3ns)forimplosioncompression,andaheatinglaserbeam(0.5–1kJ,3–5ps)forgeneratingtherelativisticelectronbeam.AfullyintegratedFIexperimentisscheduledforthe2014project.
简介:LargeapertureNd:phosphatelaserglassisakeyopticalelementforaninertialconfinementfusion(ICF)facility.N31,onetypeofneodymiumdopedphosphateglasses,wasdevelopedforhighpeakpowerlaserfacilityapplicationsinChina.ThecompositionandmainpropertiesofN31glassaregiven,togetherwiththoseofLHG-8,LG-770,andKGSS-0180Nd:phosphatelaserglasses,fromHoyaandSchott,andfromRussia.Thetechnologiesofpotmelting,continuousmelting,andedgecladdingoflargesizeN31phosphatelaserglassarebrieflydescribed.ThesmallsignalgainprofilesofN31glassslabsfrombothpotmeltingandcontinuousmeltingatvariousvaluesofthepumpingenergyofthexenonlamparepresented.N31glassischaracterizedbyastimulatedemissioncrosssectionof3.8×10-20cm2at1053nm,anabsorptioncoefficientof0.10–0.15%cm-1atlaserwavelength,smallresidualstressaroundtheinterfacebetweenthecladdingglassandthelaserglass,opticalhomogeneityof~2×10-6ina400mmaperture,andlaserdamagethresholdlargerthan42J/cm2fora3nspulsewidthat1064nmwavelength.