Neu Slwig Dw Disaces ad Times i Hydgeus Maeials i Byd May 0 005
Oulie Backgud / Lecue Maeial Neu Slwig Dw quai Flux behavi i hydgeus medium Femi eame f calculaig slwig dw disaces ad imes. Bief deivai f mea squae disace equied mdeae eu. Daa fm pape Aveage ime equied mdeae eu Daa fm pape Me Cal Simulai xplaai Oveview Wha was leaed? Refeeces
Neu Slwig Dw The pcess f educig he eegy f a eu fm he fas hemal eegy age. T deive he eu slwig dw equai fis begi wih he Neu Tasp quai. Ω + Ω Ω Ω Ω Ω + Ω Ω Ω f dd s s v dd f F 4 φ φ π ν φ By geig id f he spaial depedece f he flux we bai he slwig dw equai. + s F d S φ φ
Neu Slwig Dw c. The eegy asfe keel see i he eu slwig dw equai is: F α α α A-^ / A+^ 0 hewise Whee he fllwig assumpis ae made: i. elasic scaeig ii. age ucleus a es iii. ispic scaeig i CMCS This keel applies eu slwig dw because he eu lses eegy each ime i is scaeed by he ucleus.
Flux behavi i Hydgeus Mediums Begi wih slwig dw equai Le A meegeic pi suce a eglec abspi apply eegy asfe keel value. S S δ + + s s s S S c S c G d G cs G d S ; φ φ φ
Fudameal Quesi ad Issues Hw fa fm a pi suce des a eu f iiial eegy adm walk befe i eegy is mdeaed sme lwe eegy? > Femi addessed his pblem by esicig he eu mea fee pah λ a csa slwly vayig wih eegy. Hweve he eu scaeig c.x. f H is eihe csa slwly vayig i he eegy age 0. MeV < < 4 MeV.
Accuig f egy Depedece T deemie hw fa a eu wades befe i eaches a give lwe eegy he Femi eame is maipulaed such ha λ is w eegy depede. This mehd is valid as lg as he dmia eu scaeig mechaism is elasic ad he mea fee pah is kw.
Ne Displaceme The eu will avese a sequece f liea displacemes each emiaed by scaeig eve ha seds he eu ff i a ew dieci. Afe h pah he e displaceme R f he eu fm he igi is give by: R Image emved due cpyigh csideais. Please see: Ne Displaceme figue ake fm: Nellis W. J. Slwig-dw disaces ad imes f 0.- 4- MeV eu i hydgeus maeials. Ameica Jual f Physics 45. 5 May 977.
Bief Deivai Magiude Squaed f he Ne Displaceme R is R. R k k R + k + k csθ k Whee θ k is he agle bewee he h ad he k h pahs. Neus scae wih adial disibui fuci e -/λ whee λ is he al mea fee pah. < > λ ad < > λ <csθ k > <csθ> k- µ k-
Deivai c. Thus if λ is csa he µ µ µ µ λ R Bu if λ vaies wih eegy he The mea squaed slwig dw disace is: + + k k R µ λ λ / R R ms
Daa: 4 MeV Neu Mdeaed i Hydge N 8 x 0 cm -3 Image emved due cpyigh csideais. Please see: Neu Mdeaed i Hydge able ake fm: Nellis W. J. Slwig-dw disaces ad imes f 0.- 4- MeV eu i hydgeus maeials. Ameica Jual f Physics 45. 5 May 977.
Slwig Dw Time Aveage ime ave equied mdeae eu fm high lwe eegy is: υ ave λ Whee is he ime spe a each eegy. I he figue 4 MeV eus ae beig mdeaed f. Image emved due cpyigh csideais. Please see: Slwig Dw Time gaph ake fm: Nellis W. J. Slwigdw disaces ad imes f 0.- 4- MeV eu i hydgeus maeials. Ameica Jual f Physics 45. 5 May 977.
Me Cal Simulai The sample pblem csiss f: MeV pi suce Neus emied wih dela fuci ime disibui Pi suce a he cee f he hydge sphee Hydge desiy N 8 x 0 cm -3 Hydge sphee has a ue adius f 50 cm Pah leghs ae chse admly fm a disibui weighed by al c.x. Scaeig agle ae chse admly fm a disibui weighed by he kw agula depedece f he c.x. Lcal eegy depsied i a cllisi is he calculaed based csevai f eegy ad mmeum. Flux allies wee placed a diffee adiuses i hydge sphee s e ca mi he mdeai. f was se be 40 ev
Oveview As eegy iceases he hydge c.x. deceases; hus he al mea fee pah is lage. --- Highe eegy eus peeae deepe ha lwe eegy eus. λ T N The highe he eu eegy he fase he eu lses eegy. / flux behavi is chaaceisic f he eu disibui duig slwig dw by elasic cllisis wih age. * Hydge is he ms efficie eu mdea sice i ca absb he lages faci f eu eegy pe elasic cllisi. σ T
Refeeces Nellis W.J. Slwig-dw disaces ad imes f 0.- 4- MeV eu i hydgeus maeials. Ameica Jual f Physics Vl.45 N.5 May 977. J.R. Lamash Iduci Nuclea Reac They. 966 Neu Ieacis ad Applicais Lecue 9: Neu Slwig Dw.