How to Prepare an Experiment using the Gamma Beam System at ELI-NP

Transcription

1 EUROPEAN UNION GOVERNMENT OF ROMANIA Structural Instruments Project co-financed by the European Regional Development Fund How to Prepare an Experiment using the Gamma Beam System at ELI-NP Catalin Matei ELI-NP, Romania Carpathian Summer School of Physics, 06/2016

2 outline Gamma Beam System: layout and status GBS Parameters & Protocols Diagnostics from EuroGammaS Diagnostics developed by ELI-NP Experimental areas and instruments #ELINP #CSSP2016

3 Gamma Beam System: general layout and status

4 ELI-NP large equipment High Power Laser System - 2 x 10 PW maximum power contracted by Thales Optronique SA (~65 M ) Gamma Beam System - high intensity, tunable energy up to 20MeV contracted by EuroGammaS Consortium led by INFN Rome (~65 M )

5 ELI-NP experimental areas Anti vibration platform Platform vibrations ±1 < 10 Hz Laboratories HPLS Experimental caves GBS

6 The Gamma Beam System (GBS) gamma rays from Inverse Compton Scattering photon scattering on ultra relativistic electrons (g 1) the most efficient frequency amplifier Photon accelerator maximum upshift: head on collision (θ L =0) & backscattering (θ γ =0) E γ = 2γ 2 e 1+ ( γ θ ) e 1+ cosθ γ 2 + a 2 0 L + 4γ ee mc L 2 E L

7 Gamma Beam System Layout Photo gun e source Interaction Laser High Energy e RF LINAC High Energy 720 MeV Interaction Laser Low Energy e RF LINAC Low Energy 300 MeV Photo gun Laser

8 Gamma Beam System Layout Low Energy Gamma Beam < 3.5 MeV Photo gun e source Interaction Laser High Energy e RF LINAC High Energy 720 MeV Interaction Laser Low Energy e RF LINAC Low Energy 300 MeV Photo gun Laser

9 Gamma Beam System Layout High Energy Gamma Beam < 19.5 MeV Photo gun e source Interaction Laser High Energy e RF LINAC High Energy 720 MeV Interaction Laser Low Energy e RF LINAC Low Energy 300 MeV Photo gun Laser

10 The Gamma Beam System (GBS) Parameter [units] Value Photon energy [MeV] Spectral density [ph/s/ev] > 10 4 Bandwidth < 0.5 % # photons / shot FWHM bdw Low energy stage: Eγ < 3.5 MeV Q High energy stage: Eγ < 19.5 MeV Q # photons/sec FWHM bdw Source rms size [µm] Source rms divergence [ µrad] Peak brill. [N ph /sec. mm 2 mrad %] Radiation pulse length [ps] Linear polarization > 99 % Macro repetition rate [Hz] 100 # of pulses per macropulse >31 Pulse to pulse separation [ns] 16

11 GBS Parameters and Protocols

12 spatial & temporal parameters

13 spectral parameters

14 power parameters

15 Diagnostics from EuroGammaS

16 ! EuroGammaS diagnostics station

17 Diagnostics developed by ELI-NP

18 gamma beam - spatial parameters

19 spatial monitoring l l l CCD camera detector system, scintillator converter, mirror possible image collection at microbunch level with fast CCD design requirements: sub-mm resolution and high contrast

20 gamma beam - temporal parameters

21 temporal structure monitoring 10 ms (100 Hz) 16 ns 16 ns >31 pulses for J/pulse l l beam monitor would be placed near one of the major beam-matter interaction points: collimators, attenuator, beam dump use a small 2 x2 LaBr 3 may be able to count microbunches

22 gamma beam - spectral parameters

23 energy & bandwidth - detectors l attenuated beam l HPGe (150%) l FWHM = 2.2 kev at 1.3 MeV l LaBr 3 (3 x 4 ) l anti-compton shield l main use for energy spread w/ HPGe l possible use for intensity and time structure w/ LaBr 3 l NaI annulus 15 cm diameter, 25 cm long

24 energy & bandwidth - proposed design

25 gamma beam polarization methods l l photo-dissociation of the deuteron in the d(γ,n)p reaction significant theoretical and experimental work over the last 40 years to understand the differential cross section and polarization asymmetry l l Nuclear Resonance Fluorescence the angular distribution of the emitted gamma rays depends on the multipolarity and electric or magnetic character of the transition several candidates have been identified based on the strength of the transition and the availability of the material l l Compton scattering use the quantum mechanical Klein-Nishina differential cross section for polarized photons could also be used for beam intensity and bandwidth

26 gamma beam polarization dgn reaction

27 HIGS circular polarized beam E γ = 3 MeV E n =384 kev (ideal beam & target) Li-glass at 15 cm D 2 O target (L=4 cm, Φ=3 cm)

28 HIGS linear polarized beam E γ = 3 MeV E n =384 kev (ideal beam & target) Li-glass at 15 cm D 2 O target (L=4 cm, Φ=3 cm)

29 Y C,L Apol counts P dgn P gamma beam polarization Y L reaction YL Apol = γ flash 105 in plane YC P L BYpol YC in plane 384 kev 104 Bpol out plane + out plane Apol Ameasured pol Aexpected pol Bpol YL YC = = = 98.9% TOF (ns) Linear polarization, in-plane vs. out-of-plane P P counts L YY L C YC Y in plane plane in = P P Y LL pol= AApol Y C YC Y in plane plane in 600 P P YYLL YYCC out out plane plane P P YYLL + + YYCC out out plane plane C,L,= measured A pol ABmeasured = 0.89, pol pol expected = expectedapol = = P YC = 0.89

30 gamma beam polarization dgn reaction P IOP P S M R : April 8, 2016 R : May 12, 2016 A : May 22, 2016 P :???, 2016 Investigation of the d(,n)p reaction for gamma beam monitoring at ELI-NP C. Matei, a,1 J.M. Mueller, b,c M.H. Sikora, b,d G. Suliman, a C.A. Ur a and H.R. Weller b,d a Extreme Light Infrastructure Nuclear Physics, Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering, Bucharest-Magurele, , Romania b Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, U.S.A. c Department of Nuclear Engineering, North Carolina State University, Raleigh, North Carolina 27695, U.S.A. d Department of Physics, Duke University, Durham, North Carolina 27708, U.S.A.

31 let s design dgn instrument for ELI-NP T γ T n T 0 γ n D2 O 10 5 γ GBS 7 MeV E γ =7 MeV è E n =2.4 MeV v γ =30 cm/ns v n =2.1 cm/ns TOF (ns) distance = 35 cm T γ =T 0 +1 ns T n =T ns

32 let s design dgn instrument for ELI-NP every 16 ns n γ D2 O 10 5 γ GBS 7 MeV t t+16 t+32 t+48 TOF (ns)

33 TOF spectrum at ELI-NP T n =T ns distance = cm n D2 O γ t t+16 t+32 t+48 TOF (ns)

34 TOF spectrum at ELI-NP T n =T ns distance = cm n D2 O γ t t+16 t+32 t+48 TOF (ns)

35 gamma beam polarization dgn reaction l d(γ,n)p systems used at HIGS l D 2 O cell 4 cm long l threshold reaction 3 MeV l well known cross sections ~3% l 3-4 neutron detectors l Li-glass below 4 MeV l NE213-type above 4 MeV l beam fluence accurate to 5%

36 gamma beam - power parameters

37 gamma beam intensity dgn reaction

38 gamma beam fluence w/ fission l simple design l almost 100% efficiency l U-235, U-238, Pu-239 l areal density determined to 1% l photofission cross sections to 5% l usable above 6 MeV l P-10 gas at max 1.2 bar l beam fluence accurate to 5%

39 gamma beam fluence w/ fission l simple design l almost 100% efficiency l U-235, U-238, Pu-239 l areal density determined to 1% l photofission cross sections to 1% l usable above 6 MeV l P-10 gas at max 1.2 bar l beam fluence accurate to 2% Estimated fission rates for 200 µg target

40 summary GBS & diagnostics precise measurement of beam parameters is essential multiple monitoring devices (the more, the better) it doesn t stop here. more devices to be proposed experiments have dedicated floor space beam transport is versatile / change is possible diagnostic instruments are movable