- . , . : 1 barn = 10-24 cm-2 . () S dx /cm3 n ./sec dxSSNdx .=||

\|3 2 1 n dn=-nNdx . nx=noe-Nx=noe-x ==(/) -, Avogadro - . 2 / 1dx edx xe0x -0x -= = . 1: (7 .. & -) barns/atom, ComptonRayleigh30keV 1,03510-4, 5,92410-1 5,06210-3 2 4,247, 4,286 1,389 2.2 . : = + Comp + Rayl 30keV : ()=0,598 barn/atom ()=10,102 barn/atom 2 : (2)=2()+()=11,3 barn/mol : ( 2) .,Bragg, , . 2 : / (2) = (/) (2) = 0,378 cm2/gr : / ()= ( )W - . 3 W =1 W =1/=2,65cm 2: (10 .. & -) -10keV Be-Fe0,05cm. 18%, BeFe.(e)=1,85gr/cm2,(Fe)=7,86gr/cm3 /(Be)=0,623cm2/gr, /(Fe)=169cm2/gr. =e-x. 18% I/Io=0,82 x) ln(I/I x IIln00 = = =3,97 cm-1 1 ()=WFe(Fe)+WBe(Be) (1) WFe+WBe=1 (2) W , . Fe : I/I0(Fe)=e-(Fe)x=1,4310-29 Be I/I0(Be)=0,94 0,82 . Fe . =Be (1) (2) : WFe=0,9% WBe=99,1% Fe . - . 4 (-/) : - ( ) - Compton ( ) - ( ). . : . . - . 5 ( ). , . ep = (Ee , ep) p = ( , p) ep = (eE, ep) () (LS) ep = 0 Ee = me (ep + p)2

LS = (ep)2

LS me2 + 0 + 2 eppLS = me2 EeE epp = 0 meE = 0 E = 0 . : . - . 6 , , (80% -) . 2ME2MpT22MM = E, >> . : =30keV O2 (mn1GeV, O2 16GeV) o 0,028eV . e Te = e e.- (eV) = 13.6 (Z-1)2 . ( ),ph, Z : >> ph 5/

> ph 5/7/2

/ . - . 7 (pair production) -(e-,e+). Coulomb. : e+ + e- (CMS) = = m E 0CMS CMSp (p)2

CMS = (+p + -p)2

CMS 0 = +p2 + -p2 + 2-p+p CMS = 22em+ 2(E+E-) = 42em 0 . ( , ). Coulomb,, . () . + e+ + e- + p +p -p Np e+ e- LSCMS - . 8 : (p + p)2

LS = (+p + -p + Np)2

CMS (E + EN)2

LS (p + 0) 2

LS =(E+ + E- + EN)2

CMS - (+p + -p + Np)2

CMS (E + M)2 - 2E = (me + me + M)2 2 + 2 = 4me2 + M2 + 4meM M2m2m E2ee + = : M >> me E = 2me = 1 MeV M = me E = 4me= 2 MeV . E> m,i Ti/M 0, m/M 0). i2i i 'maxmT 2 ) M m () M 2 T ( mT 2T+ ++=i2i 2ii M1M1TMm 4MmT 2) 1Mm() 2MT( TMm 222+ ++= (2,17keV ). (=m) ii ii2i i 'maxT m 2) m 2 T ( TmT 2 ) m m () m 2 T ( mT 2T++=+ ++= =Ti - . . mM ( ) - . 15 ii ii2i i 'maxT M 2) M 2 T ( TMT 2 ) M M () M 2 T ( MT 2T++=+ ++= =Ti (m>>M, Ti/M 0) i 2M1M1i2i i 'maxT) M m (mM 4mT 2 ) M m () M 2 T ( mT 2T++ ++= m,M (GeV) i (MeV). , . , . - . 16 : ( ) () Bethe-Bloch

= 2 22ee 2e2 4 ) 1 ln(Iu m 2ln u mZ e 4dxdT : . u-2. H Bethe-Bloch . =0TdxdTdTR Wilson-Brobeck Rp(T)=8 . 13 . 9T||

\| (TMeV). e- : (/) : (eV)=16Z0.9 - . 17 Bethe-Bloch( ): 2

2=2 22 222) M T () M 2 T ( T) M T (M EEp++=+= >>, 2MT 2 MT 2m 2Ie< em 4IMT > : : (=938.3MeV, =20eV) : Al (Al=13 AAl=26,98 Al=2,7gr/cm3) =16130,9=160,94eV(>74keV, 0,5eV ) 2(=u2)=T(T+2M)/(T+M)2=4,1310-2 ln(1-2)-2=8,7710-4 ( ) ln(2meu2)/I=5,567 Ne=NA(/)=7,831023 e-/cm3 (4e/me)e4=(4Ne/me)( h ca)2=41025 MeVfm2/cm3=0,4MeV/cm -dT/dx = 0,4 (MeV/cm) (1/4,1310-2) (5,567 + 8,7710-4) -dT/dx = (53,9176 + 0,0085) MeV/cm 0,0085/53,9175=0,016% - . 18 : ; Bethe-Bloch dxdT = 2 f(u) ,f(u) . 22ppdxdTdxdT= f(u) Zp=1, Z=2 |||

\| = p dxd4dxdT =0TdxdTdTR =m(-1)=m[(1-2)-1/2-1]=(mu2)/2m=mp=100MeV =0,43. ) u ( Fmf(u) ) u ( dR2 2= = pp22pppRm 4mRZmZmRR= = m4mp R Rp - . 19 Cherenkov . () . . p=(E,p) p=(E,p) p=(E,p). : p = p + p (p p)2 = p2 p2 + p2 2pp = p2 m2 + E2 p2 2( p p) = m2 E2 p2 2+2|p||p|cos = 0 p p22 2) p - ( - 2 cos = =|p| cos=/|p|>1 . n=c/cn cn , = h = h(cn/) = (h/)(c/n) = (c/n)|p| 22222 n 21 nnE21nc-nc2 cos+ =|||

\|=ppp p pp p eV ( ) |p|/||p| 0, n 1n cos = =p (,p) (,p) (,p) - . 20 cos1 n1 Cherenkov. 2 =arcos n1 . Cherenkov = m = m - m = m[(1-2)-1/2 1] m [(1-2n1)-1/2 1] p2 = E2 m2 = m2 (2 - 1) p = m (2 1)1/2 = m(1-2)-1/2 p mn1 (1-2n1)-1/2 |||

\| = 2 2 2 22 21dE En 11ce ZdxdEh : (8 .. & -) Cherenkov (n=1,33)(me=0,51MeV),(m=139,6MeV) (mp=938,3MeV).,p Cherenkov ; =0,517m e=0,264MeVT=72,14MeV p=484,88MeV. (0,26MeV). -Compton - . 21 . Cherenkov . Cherenkov: p=159,2eV pp=1069,7MeV 159,2MeV1069,7MeV. Cherenkov, ( ). : ( ) , 10GeV. Cherenkov, , P (atm) : n=1+310-4P m=0,140GeV, m=0,494GeV, mp=0,938GeV. p =mn1 (1-2n1)-1/2 1 )pm( n )pm( 1 n)n11 ( nmp2222222+ = = = n=1+310-4P 4 210 ) 1 1 )pm( (31) atm ( P + = p=10GeV . m(GeV)P(atm) 0,1400,327 0,4944,065 0,93814,632