ONSET OF THE QUANTUM REGIME KRISTOFFER K. ANDERSEN DEPARTMENT OF - PowerPoint PPT Presentation

22. FEBRUARY 2013 EXPERIMENTAL INVESTIGATIONS OF SYNCHROTRON RADIATION AT THE ONSET OF THE QUANTUM REGIME KRISTOFFER K. ANDERSEN DEPARTMENT OF PHYSICS AND ASTRONOMY, AARHUS UNIVERSITY QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN

MOTIVATION › Test of quantum mechanical calculations of synchrotron radiation. › Relevant for linear colliders, astrophysical objects like magnetars, heavy ion collisions and more. Magnetar SGR 1900+14 QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 2

BEAMSTRAHLUNG › Electric field from one bunch boosted by 2 g 2 -1 as seen by particles in the other bunch The electric field of the oncoming Small beams, high Lorentz factors => bunch is seen as a Strong electromagnetic fields => magnetic and Beam focusing electric field in the Increase of luminosity rest frame of the first Beamstrahlung bunch. QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN

SYNCHROTRON RADIATION › Typical radiated energy is › The strong field parameter › The critical field is B photons electrons QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN

SYNCHROTRON RADIATION Classical synchrotron radiation 1 0 In cid e n t e n e rg y, E e =1 0 G e V 1  dN/d  Critica l e n e rg y 0 .1 0 .0 1 S ta n d a rd ma g n e t, B = 1 T, 1 m S i <1 1 0 > max , B equiv = 2 5 .0 0 0 T, 0 .1 mm 0 .0 0 1 0 .0 0 1 0 .0 1 0 .1 1 1 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 0 Photon energy [M eV] QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN

BEAMSTRAHLUNG PARAMETERS › For colliders the strong field parameter is given by › And the luminosity is without disruption. › separates the classical from the quantum regime. QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN

CLIC PARAMETER › For CLIC we get From the CLIC conceptual design report › However due to disruption of the beam the averaged parameter › For ILC this is is QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN

CLIC LUMINOSITY › Large reduction due to beamstrahlung but even worse if the quantum suppression was not present- From the CLIC conceptual design report QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN

MAGNETARS › B = 10 GT > B 0 › Neutron star of radius 20 km and greater mass than the sun. › Gamma and X-ray emitters On the surface of quark stars QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 9

THE NA63 EXPERIMENTS › Use crystalline fields to measure the quantum corrections to synchrotron radiation. QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 10

EXPERIMENTAL SETUP DC1 DC2 Krystal QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 11

GERMANIUM CRYSTAL Random orientation axis QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 12

CONTINUUM MODEL QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 13

CRYSTAL POTENTIAL AND FIELD Strong field parameter Remark the figure shows the potential energy for a positron along the crystal axis The potential is taken from Baier et al. QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 14

ACCESSIBLE PHASE SPACE The potential energy at a given distance from the axis The transverse kinetic energy The particle is free to move between different axes. Well channelled particles have extremely small entrance angles. QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 15

THE CONSTANT FIELD APPROXIMATION Radiation emission angle: Deflection angle: Criterium for constant field approx. Magnetic bremsstrahlung QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 16

THE CONSTANT FIELD APPROXIMATION › Classical synchrtron radiation › The constant field approximation › Two changes: Spin and recoil QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 17

THE CONSTANT FIELD APPROXIMATION › Spin contribution: NIMB 119 (1996) 2 QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 18

CRYSTAL RADIATION Average over positions in crystal. Strong field parameter For germanium QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 Baier et al. KRISTOFFER K. ANDERSEN 19

RADIATION ENHANCEMENT › Radiation emission is enhanced compared to bremsstrahlung. › Bethe-Heitler formula: QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 20

DEFLECTION AND DETECTION DC2 DC3 Crystal MBPL magnet LG QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 21

PILE UP AND CALOMETRIC EFFECT Lead glass detector Photon energy Multiphoton effects: Less photons at low energies A slight increase at high energies QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 22

PAIR SPECTROMETER DC5 DC6 Cu conver- MDX magnet siontarget QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 23

GEOMETRIC CONSTRAINTS 3.2 m 2.0 m e - q - Drift chamber width: 15 cm q + MDX e + DC6 DC5 DC6 angle constraint: corresponding to Energy threshold: for DC6. QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 24

GEOMETRIC CONSTRAINTS QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 25

MONTE CARLO SIMULATIONS OF PS › Compare the background measurements to the Bethe-Heitler formula. PRD 86, 072001 (2012) QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 26

MONTE CARLO SIMULATIONS OF PS › The goal is to verify measurements of Bethe-Heitler radiation and determine the efficiency of the pair spectrometer. PRD 86, 072001 (2012) QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 27

PAIR SPECTROMETER EFFICIENCY › From the Monte Carlo simulations we deduce the efficiency of the pair spectrometer from the incident photons and the measured spectrum. › Depends on: Detector geometry Conversion probability Internal structure of detector Drift chamber efficiency QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 28 PRD 86, 072001 (2012)

RADIATION SPECTRA QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 PRD 86, 072001 (2012) KRISTOFFER K. ANDERSEN 29

RADIATION SPECTRA 100 GeV data › Full theoretical calculation › Single field CFA fit with and without the spin correction. › Classical synchrotron radiation QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 PRD 86, 072001 (2012) KRISTOFFER K. ANDERSEN 30

ENHANCEMENT Quantum suppression of synchrotron radiation QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 31

SPIN FLIP TRANSITIONS QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 32

SPIN FLIP TRANSITIONS ’Polarization time’ For a 100 GeV electron in χ = 1 field c t becomes 10 μm or t = 32 fs PRL 87, 054801 (2001) QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 33

THE CONCEPT OF FORMATION LENGTH › The distances the emitted photon travels before it is separated by a Compton wavelength from the emitting electron. High particle energy, low photon energy: Long formation length 250 GeV e - , 1 GeV γ : l f = 0.1 mm QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 34

THE CONCEPT OF FORMATION LENGTH › For synchrotron radiation one can relate the magnetic field to the formation length. For a 100 GeV electron in a 1 kT field this corresponds to a 9 GeV photon. QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 35

A SIMPLE GRAPHICAL EXPLANATION QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 36

DIRECT MEASUREMENT OF L F › 45 μ m target separation › Small excess around 400 MeV › Data has a preference for the Blankenbecler and Drell theory with the delta correction term. QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 37

CRYSTALLINE UNDULATORS › Periodically bent crystals consisting of silicon and germanium and made by molecular beam epitaxy. › Amplitude a > d › Stable channelling › Many periods › Low radiative loss QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 38

CRYSTALLINE UNDULATORS › Measured at MAMI › 270 MeV electrons in planar channelling for a flat crystal (blue) and crystal undulator (red). › The excess is seen around the 1st harmonic at 70 keV. QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 39

THANKS TO the CERN NA63 collaboration in which this work was done. Aarhus University: Other members of NA63 Aarhus University: Group of Ulrik Uggerhøj; Pietro Sona Technical staff: Alessio Mangiarotti Helge Knudsen Per Christensen Sergio Ballestrero Heine Thomsen Poul Aggerholm Tjeerd Ketel Jakob Esberg Søren Andersen And thanks for your attention! QUANTUM SYNCHROTRON RADIATION 22. FEBRUARY 2013 KRISTOFFER K. ANDERSEN 40