BREMSSTRAHLUNG IN A THIN LAYER OF MATTER AT HIGH ENERGY

Transcription

1 BREMSSTRAHLUNG IN A THIN LAYER OF MATTER AT HIGH ENERGY S.P. Fomin, A.S. Fomin, N.F. Shul ga Akhiezer Institute for Theoretical Physics National Science Center Kharkov Institute of Physics & Technology Kharkov 61108, Ukraine, sfomin@kipt.kharkov.ua

2 Content: 1. SLAC experiment E-146. Theory of the LPM effect 3. Radiation in a thin layer of matter 4. CERN experiment NA63 5. Spectral-angular distribution of radiation 6. Polarization at non-dipole regime of radiation 7. Conclusion

3 1. SLAC experiment E-146 3

4 1. SLAC experiment E Anthony P.L. et al., Phys. Rev. Lett. 75 (1995) F.F. Ternovskii. JETP 1(1961)13.

5 . Theory of the LPM effect 5 Multiple scattering effect on radiation of relativistic electron in amorphous medium p / p l c k 0 L L.D. Landau, I.Yu. Pomeranchuk, Dokl. Akad. Nauk SSSR 9 (1953) ϑ l c > γ : suppression of radiation : l = εε '/ m ω c de dω LP de < dω BH

6 Quantitative theory of the effect in a boundless amorphous medium: A.B. Migdal, Dokl. Akad. Nauk SSSR 96 (1954) 49; JETP 3 (1957) de dω LPM = debh dω M ( s), ( s) M π = 4s dt cth t e st sin st 4 0 de H 4 = dω 3 T L s = 1 ω ω LPM 4 ωlpm = q γ ~ γ ε s 1 q = ε L E LPM d dω ~ ω

7 SLAC experiment E Klein S., Rev. Mod. Phys. 71 (1999) 1501.??? γ ϑ < 1 γ ϑ > 1, but T < l c γ ϑ > 1 and T > l c

8 8 3. Radiation in a thin layer of matter lc >> T V Shul ga N.F., Fomin S.P., JETP Letters 7 (1978)16. Fomin S.P., Shul ga N.F., Physics Letters A114 (1986)148. x V / s k z l coh 0 T I = i d E e ω = dωdο 4π dt e i ( ωt kr( t )) [ n I ] d dt v ω kv lc >> T v v : I i ω kv ω kv 3e ξ, ξ, de << 1 π dω e ln( ξ ), 4 ξ >> 1. π ; de e ξ + 1 = ln( ξ + ξ + 1) 1, dω π ξ ξ + 1 de T, ξ << 1, dω lnt, ξ >> 1. ξ = 1 γϑ

9 Quantitative theory of radiation in a thin layer of matter: 9 Shul'ga N.F., Fomin S.P., JETP Lett. 63 (1996) 873; JETP 86 (1998) 3; NIM B145 (1998) 73. de dω de d s f( s) 1 4, f dω B M( ϑ ) = ηdηj 0( ηϑ)exp χc χ dχ q( χ) χ [ 1 J 0( ηχ) ] 0 0 = ϑ ϑ γ ϑ > 1 : ( ) d a a B B ln B = ln( ε R χ ) + 1 C, π de e C = ln a C ω π, c, 4 χ c = 4π nlz e / ε, C = 0,577 a = γ ϑ, ϑ = χ B c, dε dω Au E = 50 GeV = 5 GeV B-H 1 GeV LPM 0. GeV S-F L, % L R

10 10 Other publications: R. Blankenbacler, S.D. Drell. The Landau-Pomeranchuk-Migdal effect for finite targets. Phys.Rev. 1996, v. D53, p R. Blankenbacler. Structured targets and Landau-Pomeranchuk-Migdal Effect. Phys. Rev. 1997, v. D55, p B.G. Zhakharov. Structured targets and Landau-Pomeranchuk-Migdal effect for finite-size targets. JETP Lett. 1996, v. 64, p B.G. Zhakharov. Light-cone path integral approach to the Landau-Pomeranchuk-Migdal effect. Yadernaya Fiz. 1998, v. 61, p R.Baier, Yu.L.Dokshitser, A.H.Mueller, S.Peigne, D.Schiff. The Landau-Pomeranchuk-Migdal effect in QED Nucl. Phys. 1996, v. B478, p V.N. Baier, V.M. Katkov. Landau-Pomeranchuk-Migdal effect and transition radiation in structured targets. Phys. Rev. 1999, v. D60, , 1 p

11 Reviews: 11 A.I. Akhiezer, N.F. Shul'ga, S.P. Fomin. The Landau-Pomeranchuk-Migdal Effect. Cambridge Scientific Publishers, Cambridge, UK, 005, 15 p. S. Klein. Suppression of bremsstrahlung and pair production due to environmental factors. Rev. of Mod. Phys. 1999, v. 71, p A.I. Akhiezer, N.F. Shul ga. High-energy electrodynamics in matter. Amsterdam: Gordon and Breach, 1996, 388 p. A.I. Akhiezer, N.F. Shul ga. The effect of multiple scattering on relativistic particle radiation in amorphous and crystal media. Sov.Phys.Uspekhi. 1987, v.30, p M.L. Ter-Mikaelian. High-energy electromagnetic processes in condensed matter. New York: Wiley Interscience, 197, 457 p.

12 4. CERN experiment NA63 (005) 1

13 4. CERN experiment NA63 (005) 13 Results of our calculations: dn Xo dω t 0.5 Au t = 10 µm E = 178 GeV dn Xo dω t 0.5 W t = 0 µm E = 178 GeV TSF BH BH LPM 0.1 t = l c LPM ω, GeV ω, GeV

14 4. CERN experiment NA63 (008) 14 Phys.Lett.B 008 (in print) Abstract

15 4. CERN experiment NA63 15 (008) D.H.Thomsen et al. Phys.Lett.B 008 (in print) Channeling 008 Serguei Fomin et al. AITP NSC KIPT

16 16 de Xo dω t TSF/LPM Ta E = 06 GeV TSF/LPM BH TSF LPM ω, GeV de Xo dω t TSF/LPM Ta E = 34 GeV TSF/LPM BH TSF LPM ω, GeV

17 5. Spectral-angular distribution of radiation l coh >> T 17 Fomin S.P., Shul'ga N.F. and Shul'ga S.N., Phys. of Atomic Nuclei 66 (003) 396. d d E e γ = dο π 1+α +α β + αβ cosϕ 1+α +β αβ cosϕ ( 1+α ) ( 1+α +β αβ cosϕ) ω α = γϑ k, β = γϑe 1 1, x V / V s k z 0 T l c

18 Polarization at non-dipole regime of radiation ϑ l c > γ e ω = 4 π Polarization matrix: Jik ( ei I)( ek I ), i,k e n = 0, e e = δ. i k ik Linear polarization: J J P = J + J Circular polarization: P c = J J J + J l T : coh Jik Jki = => P = c 0 for any angles of observation.

19 Dipole regime of radiation: ϑ l c < γ 1 19

20 1 Non-dipole regime of radiation: ϑ l c > γ 0

21 1

22 Conclusion The multiple scattering effect on radiation spectrum of ultra-relativistic electrons in a thin layer of matter (TSF effect) was observed successfully at CERN experiment NA63 for electron energies 06 and 34 GeV. The multiple scattering effects significantly the spectral-angular distribution of radiation of ultra-relativistic electrons in a thin amorphous target and in aligned crystal. The special features of non-dipole regime of ultra-relativistic electron radiation in aligned crystals can be used to obtain the linear polarized high intensity photon beam with vertical and horizontal direction of polarization simultaneously. It is necessary to carry out the corresponding experimental investigation to verify mentioned above effects in spectral-angular distribution of radiation and its polarization.