1. X-ray and γ-ray polarimetry Stanislav Tashenov KTH Stockholm

2. Outline Definitions Photon Polarimetry - Short Overview Principle – Klein-Nishina formula Pixel Detector – coincident technique Experimental study of the polarization of Radiative Recombination From experimental setup till results Summary Compton Polarimetry of hard X-rays New developments of Compton polarimeters for “low” energies (few 100 keV) Extension of Compton polarimetry to higher energies, tracking (till few 10 MeV) Compton circular polarimetry Other types of polarimeters Photoelectric Pair production Crystalline

3. What is photon polarization? Classical: polarization of electromagnetic waves linear: Quantum Mechanical: photon helicity S S λ = 1 λ = -1 circular: λ = 1 λ = -1 Linear polarization – superposition of states with opposite helicities

4. What is partial photon polarization? Mixed state is described by a density matrix: Linear polarization components: Circular: polarization ellipse Stokes parameters

5. Rayleigh (elastic) scattering Wollaston and other prisms Photon polarimetry & imaging energy, ev 11e41e51e61e7101001e31e81e91e100.1 Birefringence effect Linear dichroism LCD IR visible light UV soft X-ray X-ray hard X-ray gamma → Bragg reflection Photoabsorption x-ray optics Micropattern gas counters Thomson scattering CCD cameras Segmented solid state detectors Chandra X-ray image of Crab Nebula and Compton scattering

6. Photon polarimetry & imaging energy, ev

7. Photon polarimetry & imaging energy, ev Wollaston and other prisms 11e41e51e61e7101001e31e81e91e100.1 Birefringence effect Linear dichroism LCD IR visible light UV soft X-ray X-ray hard X-ray gamma → Bragg reflection Photoabsorption x-ray optics Micropattern gas counters Thomson scattering CCD cameras Segmented solid state detectors and Compton scattering Pair production Birefringence in CPP AGATA, GRETA Advanced Compton Telescope

8. Outline Definitions Photon Polarimetry - Short Overview Principle – Klein-Nishina formula Pixel Detector – coincident technique Experimental study of the polarization of Radiative Recombination From experimental setup till Results Summary Compton Polarimetry of hard X-rays New developments of Compton polarimeters for “low” energies (few 100 keV) Extension of Compton polarimetry to higher energies, tracking (till few 10 MeV) Compton circular polarimetry Other types of polarimeters Photoelectric Pair production Crystalline

9. recoil electron scattered photon  e-e- cc  Compton scattering

10.  E   ´   E Klein-Nishina equation Compton polarimetry Modulation

11.  coincidence  E el E=   E=  el +   single pixel spectrum recoil electron Compton photon 4 x 7 mm 15 mm 4 x 7 mm coincident sum spectrum Segmented detectors – coincidence technique

12.  e-e- cc recoil electron scattered photon Compton kinematics For higher energies the reconstruction is more difficult → Tracking is required

13. Outline Definitions Photon Polarimetry - Short Overview Principle – Klein-Nishina formula Pixel Detector – coincident technique Experimental study of the polarization of Radiative Recombination From experimental setup till results Summary Compton Polarimetry of hard X-rays New developments of Compton polarimeters for “low” energies (few 100 keV) Extension of Compton polarimetry to higher energies, tracking (till few 10 MeV) Compton circular polarimetry Other types of polarimeters Photoelectric Pair production Crystalline

14. Radiative Recombination Time Reversal Photoionization e - h  Radiative Electron Capture 8 E L E K E KIN e - h  U 92+ → N 2 collision at 310 MeV/u 150 ○ observation angle

15. Photon Polarization e-e- E Radiative Electron Capture Photoionization non-relativistic dipole approximation: 100 % polarization for all emission angles

16. K-REC photon polarization K-REC into bare uranium ions (U92 + + e -  U91 + + ħω ) non-relativistic dipole approximation: 100 % polarization for all emission angles Large relativistic contributions J. Eichler et al., PRA, 65 (2002) 052716 A. Surzykov et al., Phys. Lett. A 289 (2001) 213 A. Surzykov et al., PRA 68 (2003) 022710 e-e- e-e- along the magnetic field along the electric field

17. e - cooler GAS JET ∙ U 92+ stored at energies of 98.4, 132.2, 190.0, 400.0 MeV/u ∙ Number of stored particles 1 to 3x10 8 ∙ Energy definition 10 -4 with cooling GAS JET N 2 10 12 p/cm 2 SIS injection 400 MeV/u Particle detector 90 o 60 o REC measurement at the ESR storage ring

18. ion beam (400 MeV/u) target gas K-REC ESR storage ring I∥I∥ I⊥I⊥ I⊥I⊥ I∥I∥ Experiment: Polarization Measurement for Radiative Recombination Transitions (U 92+ + e -  U 91+ + ħω )

19. 90º 90 ○ rotational symmetry of the detector Result (400 MeV/u, 90 o observation angle) degree of linear polarization: polarization angle: 0.79 ± 0.08 0 o ± 3 o Compton scattering angular distribution: Internal normalization

20. Monte-Carlo simulation describing the detector response to polarized light  e-e- cc Z=14±1 mm Compton profile Rayleigh scattering Statistical error ±4 % up to ±12 % Overall error is dominated by the statistical uncertainty Multiple Compton scattering Detector geometry All systematic effects ±2 % up to ±3 % --- < +0.5 % ±2 % up to ±3 % --- estimated uncertainty: (+1.3 % shift) (detector depletion depth)

21. Angular dependence Energy dependence θ=60 o Uranium (Z=92) Results S. Tashenov et al., PRL 97 (2006) 223202

22. Ψ ion beam E S Ion beam spin polarization Uranium 500 MeV/u  degree of ion beam spin polarization ⇒ A.Surzhykov et al., PRL 94 (2005) 203202

23. Outline Definitions Photon Polarimetry - Short Overview Principle – Klein-Nishina formula Pixel Detector – coincident technique Experimental study of the polarization of Radiative Recombination From experimental setup till results Summary Compton Polarimetry of hard X-rays New developments of Compton polarimeters for “low” energies (few 100 keV) Extension of Compton polarimetry to higher energies, tracking (till few 10 MeV) Compton circular polarimetry Other types of polarimeters Photoelectric Pair production Crystalline

24. Further developments of Compton polarimeters Optimization for lower energies (~60 keV) 2D Si(Li) stripe detector 2 mm stripe width stack of 10 DSSD 2 mm stripe width

25. Further developments of Compton polarimeters Increased segmentation for better polarization sensitivity 2D Ge μ-stripe detector 0.25 x 1.2 mm stripe width   ´   E Scattering angle θ is selected by the energy condition 30 45 65 90 115 135 150 165 205 188 170 149 133 123 119 116 energy [keV] scattering angle [deg] Preliminary results: 210 keV Test experiment at ESRF, 2005

26. Further developments of Compton polarimeters 3D position sensitivity achieved by means of digital signal processing Pulse Shape Analysis 2D pixel detector with 10 mm pixel size → 1 ÷ 3 mm 3D position resolution KTH Stockholm Ge 5 x 5 pixel detector 10 mm pixel size equipped with digital pulse sampling electronics Laboratory calibration as a polarimeter preliminary results

27. Outline Definitions Photon Polarimetry - Short Overview Principle – Klein-Nishina formula Pixel Detector – coincident technique Experimental study of the polarization of Radiative Recombination From experimental setup till results Summary Compton Polarimetry of hard X-rays New developments of Compton polarimeters for “low” energies (few 100 keV) Extension of Compton polarimetry to higher energies, tracking (till few 10 MeV) Compton circular polarimetry Other types of polarimeters Photoelectric Pair production Crystalline

28. Extension to higher energies Gamma-ray tracking is required Solution: BGO shielding or Close-packed geometry

29. How well do the scattering angles fit with the corresponding deposited energies? Tracking principle

30. Performance of tracking Tracking can: 1)determine the sequence of the scatterings 2)verify the full energy deposition 3)obtain the initial energy for the escape events initial spectrum full energy events escape events

31. Gamma arrays for nuclear physics based on tracking principles AGATA (EU) GRETA (US) DESPEC (GSI, darmstadt) J. Simpson, J. of Phys.: Conf. Ser. 41 (2006) 72-80 I.Y. Lee et al., Nucl. Phys. A 746 (2004) 255c-259c Application of linear polarization: radiation from aligned excited states - Identification of electric and magnetic transitions g-factor measurements – time variation of linear polarization J. Rikovska, Hyperf. Int. 24-26 (1985) 963 G.J. Schmid et al., NIMA 417 (1998) 95

32. Gamma arrays for astrophysics Nuclear Compton Telescope balloon-borne mission Advanced Compton Telescope space mission S.E. Boggs, P. Jean, Astronomy and Astrophysics 376 (2001) 1126 J.D. Kurfess et al., New Astronomy Reviews 48 (2004) 293 „Gamma-ray polarization will be used to study the emission processes in GRBs, pulsars, AGN, and solar flares—opening a new dimension in diagnostic phase space.“ (27 layers of Si and 4 layers of Ge) (12 Ge detectors)

33. Outline Definitions Photon Polarimetry - Short Overview Principle – Klein-Nishina formula Pixel Detector – coincident technique Experimental study of the polarization of Radiative Recombination From experimental setup till results Summary Compton Polarimetry of hard X-rays New developments of Compton polarimeters for “low” energies (few 100 keV) Extension of Compton polarimetry to higher energies, tracking (till few 10 MeV) Compton circular polarimetry Other types of polarimeters Photoelectric Pair production Crystalline

34. Compton circular polarimetry Circularly polarized light couples only to spin-oriented electrons W.H.McMaster, Review of Modern Physics 33 No.1 (1961) 8 k, k 0 – final and initial photon energies k, k 0, S – photon and electron momenta

35. Compton circular polarimetry: technical realization H. Schopper, Nuclear Instruments 3 (1958) 158 L.W. Fagg, S.S. Hanna, Review of Modern Physics 31 No.3 (1959) 711 2 out of 26 electrons of Fe can be spin oriented for Compton scattering the opposite spins of the electron and the photon are preferable

36. Compton circular polarimetry: examples of applications E.G. Adelberger, Ann. Rev. Nucl. Part. Sci. 35 (1985) 501 W.C. Haxton, C.E. Wieman, Annu. Rev. Nucl. Part. Sci. 51 (2001) 261 L. N. Labzowsky et al., PRA 63 (2005) 054105 M.J. Cooper et al., Radiation Physics and Chemistry 75 (2006) 1638 F. Lei et al., Space Science Reviews 82 (1997) 309 J.C. Kemp, The Astrophysical Journal 162 (1970) 169 Studies of parity violation and tests of the standard model of elementary particles Neutrino helicity (Goldhaber experiment) Astrophysics: light emission from strongly magnetized media Magnetic Compton scattering: measurements of spin distributions in magnetic research Thomson scattering off relativistic electron beams to determine its properties

37. Outline Definitions Photon Polarimetry - Short Overview Principle – Klein-Nishina formula Pixel Detector – coincident technique Experimental study of the polarization of Radiative Recombination From experimental setup till results Summary Compton Polarimetry of hard X-rays New developments of Compton polarimeters for “low” energies (few 100 keV) Extension of Compton polarimetry to higher energies, tracking (till few 10 MeV) Compton circular polarimetry Other types of polarimeters Photoelectric Pair production Crystalline

38. Photoelectric polarimeters ~ 1 up to few 10 keV E. Costa et al., Nature 411 (2001) 662 R. Bellazzini et al., NIMA A 576 (2007) 183

39. Photoelectric polarimeters ~ 1 up to few 10 keV R.P. Pratt et al., “Polarization correlations in atomic photoeffect”, Phys. Rev. 134 No 4a (1964) 916 Cross over happens at much higher energies non-relativistic dipole approximation: 100 % polarization for all emission angles e-e- along the magnetic field

40. Pair production polarimeters ~ few MeV up to ~ 1 GeV P.F. Bloser et al., arXiv:astro-ph/0308331 (2003) Problem at lower energies: angle straggling of electrons and positrons in solids Solution: Gas micro well detectors

41. Crystalline polarimeters > few GeV N. Cabibbo, PRL 9 (1962) 270 N. Cabibbo, PRL 9 No10 (1962) 435 U. Uggerhoj Rev. Mod. Phys. 77 (2005) 1131 A. Apyan et al., arXiv:hep-ex/0512017 v1 (2005)

42. In collaboration with......the end. Th. Stöhlker D. Banas A. Gumberidze A. Muthig R. Reuschl U. Spillmann M. Trassinelli S. Trotsenko GSI, Darmstadt Experiment A. Surzhykov S. Fritzsche GSI, Darmstadt Theory D. Proic Th. Krings FZ-Jülich Detectors J. Eichler Hahn-Meitner-Institut Berlin Theory J. Gerl GSI, Darmstadt Experiment R. Schuch S. Bohm Uni. Stockholm Experiment EBIT nuclear γ-spec Bo Cederwall A. Khaplanov KTH Stockholm Experiment nuclear γ-spec ESR

43. Bragg polarimetry P. Soffitta et al., "Techniques and detectors for polarimetry in X-ray astronomy" NIMA 510 (2003) 170 E.E. Alp et al., "Polarizer–analyzer optics" Hyperfine Interactions 125 (2000) 45 P. Beiersdorfer et al., "Polarization of K-shell x-ray transitions of Ti19+ and Ti20+ excited by an electron beam" PHYSICAL REVIEW A 60 (1999) 4156 Photoelectric polarimetry R. Bellazzin et al., "A photoelectric polarimeter for XEUS: a new window in x-ray sky" arXiv:astro-ph/0609571v1 (2006) E. Costa et al., "An efficient photoelectric X-ray polarimeter for the study of black holes and neutron stars" Nature 411 (2001) 662 E. Costa et al., "OPENING A NEW WINDOW TO FUNDAMENTAL PHYSICS AND ASTROPHYSICS: X-RAY POLARIMETRY" arXiv:astro- ph/0603399 (2006) J.K. Black et al., "X-ray polarimetry with an active-matrix pixel proportional counter" NIMA 513 (2003) 639 Compton polarimetry F. Lei et al., "Compton polarimetry in gamma-ray astronomy" Space Science Reviews 82 (1997) 309–388 M.L. McConnell, J.M. Ryan "Status and prospects for polarimetry in high energy astrophysics" New Astronomy Reviews 48 (2004) 215–219 Hiroyasu Tajima et al.,"Gamma-ray Polarimetry with Compton Telescope" (2004) arXiv:astro-ph/0407114 R.A. Kroeger et al., "Gamma ray polarimetry using a position sensitive germanium detector" NIMA 436 (1999) 165 L.W. Fagg "Polarization measurements on nuclear gamma rays" Review of Modern Physics 31 No3 (1959) 711 W. McMaster "Matrix representation of polarization" Review of Modern Physics 33 No1 (1961) 8 G.J. Schmid et al., "Gamma-ray polarization sensitivity of the Gammasphere segmented germanium detectors" NIMA 417 (1998) 95 J.H. Lee et al., "Polarization sensitivity and efficiency for a planar-type segmented germanium detector as a Compton polarimeter" NIMA 506 (2003) 125 J. Rikovska, "Gamma-ray linear polarization measurements on oriented nuclei" Hyperfine Interactions 24-26 (1985) 963 Dan Xu et al., "Detection of Gamma Ray Polarization Using a 3-D Position-Sensitive CdZnTe Detector" IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 52, NO. 4, (2005) 1160 S. Tashenov et al., "First Measurement of the Linear Polarization of Radiative Electron Capture Transitions" Physical Review Letters, 97, 223202 (2006) Circular Compton polarimetry H. Schopper, "Measurement of circular polarization of gamma-rays" Nuclear Instruments 3 (1958) 158 L.W. Fagg "Polarization measurements on nuclear gamma rays" Review of Modern Physics 31 No3 (1959) 711 R.M. Steffen, Physical Review 118 No.3 (1960) 763-767 R.E. Pechacek et al., Review of Scientific Instruments 35 No.1 (1964) 58-63 R.D.L. Mackie, J. Byrne, Nuclear Instruments and Methods 76 (1969) 241-244 W. Trautmann et al., Physical Review Letters 39 No.17 (1977) 1062-1065 T.F. Fazzini et al., Nuclear Instruments and Methods 192 (1982) 287-290 V.A. Kniaz'kov et al., Nuclear Physics A 417 (1984) 209-230 Pair production polarimetry M. Kobayashi et al., "New method for measurement of gamma-ray polarization by detection of angular correlation in pair production" NIM 104 (1972) 101 P.F. Bloser et al., "A Concept for a High-Energy Gamma-ray Polarimeter" arXiv:astro-ph/0308331 (2003) B. Wojtsekhowski et al., "A pair polarimeter for linearly polarized high-energy photons" NIMA 515 (2003) 605 Crystalline polarimetry N. Cabibbo et al., "New method for producing and analyzing linearly polarized gamma-ray beams" Physical Review Letters 9 no6 (1962) 270 N. Cabibbo et al., "Circular polarization of high-energy gamma-rays by birefringence in crystals" Physical Review Letters 9 no10 (1962) 435 U. Uggerhoj "The interaction of relativistic particles with strong crystalline fields" Review of Modern Physics 77 (2005) 1131 A.Apyan et al., "Coherent Bremsstrahlung, Coherent Pair Production, Birefringence and Polarimetry in the 20-170 GeV energy range using aligned crystals" arXiv:hep-ex/0512017 v1 (2005) http://www-linux.gsi.de/~tachenov/research/talks/polarimetry.pdf X-ray polarimetry publications Thank you for your patience!