ACTAR TPC: an active target and time projection chamber for nuclear physics. 17/09/2015 T. Roger COMEX 5 1

Transcription

1 ACTAR TPC: an active target and time projection chamber for nuclear physics 17/09/2015 T. Roger COMEX 5 1

2 Nuclear structure through transfer reactions Past: structure of nuclei close to stability in direct kinematics, use of magnetic spectrograph q Good resolution (few kev) q High beam intensity q Stuck with stable isotopes from which a target can be made J.E. Spencer and H.A. Enge, NIM 49, 181 (1967) 17/09/2015 T. Roger COMEX 5 2

3 Nuclear structure through transfer reactions Now: structure of exotic nuclei in inverse kinematics q Study of nuclei with short half-life q Low beam intensity q Resolution strongly depends on target thickness 28 Si CD 2 p Detector(s) 82 Ge p Detector(s) 29 Si 83 Ge 100 kev FWHM 80 µg/cm kev FWHM 430 µg/cm 2 J.C.Lighthall et al., NIM A (2010) J.S. Thomas et al., PRC 71, (2005) Need thick targets and excellent resolution 17/09/2015 T. Roger COMEX 5 3

4 Nuclear structure through transfer reactions Now: ACTIVE TARGETS q Study of nuclei with short half-life, produced with small intensity q Use of thick target without loss of resolution q Detection of very low energy recoils Active target: (Gaseous) detector in which the atoms of the gas are used as a target 17/09/2015 T. Roger COMEX 5 4

5 When should active targets be used? q Reactions with very negative Q-value in inverse kinematics à recoil stops inside the target 68 Ni(α,α 50A MeV GMR Q -15 MeV 8 He( 19 F, 20 Ne) 7 15A MeV Q -13 MeV M. Vandebrouck, PhD thesis, Université Paris-Sud XI (2013) 17/09/2015 T. Roger COMEX 5 5

6 When should active targets be used? q Reactions with very negative Q-value in inverse kinematics à recoil stops inside the target q Study of excitation functions à thick target, need to differentiate the reaction channels T. Roger, PhD thesis, Université de Caen (2009) 17/09/2015 T. Roger COMEX 5 6

7 When should active targets be used? q Reactions with very negative Q-value in inverse kinematics à recoil stops inside the target q Study of excitation functions à thick target, need to differentiate the reaction channels q Reactions with very low intensity beams à thick target, possibly no 12 C contamination Example: 132 Sn(d,p) reaction à For the same energy loss in the target, about 3x more deutons in D 2 gas than in solid CD 2 target à Vertexing: possibility to increase the target thickness without loss of resolution è Overall gain of D 2 gaseous target: factor up to 100! ACTARsim report: 17/09/2015 T. Roger COMEX 5 7

8 1 st active target in France: MAYA MAYA: A two dimensional charge one dimensional time projection chamber Cathode recorded pattern à 2 dimensions (32x32 pads) Wire recorded time à 3 rd dimension (32 wires) C.E. Demonchy et al., NIM A 583, 341 (2007) 17/09/2015 T. Roger COMEX 5 8

9 MAYA: Achievements q 1 st observation of Giant Resonances in radioactive nuclei: 56 Ni & 68 Ni C.Monrozeau et al. Phys. Rev. Lett. 100, (2008) M. Vandebrouck et al. Phys. Rev. Lett. 113, (2014) M. Vandebrouck et al. Phys. Rev. C 92, (2015) S. Bagchi et al. Submitted to Phys. Lett. B (2015) q Observation of the most exotic nucleus 7 H M.Caamano et al. Phys. Rev. Lett. 99, (2007) q 1 st study of the 11 Li 2-neutron halo via a transfer reaction I.Tanihata et al. Phys. Rev. Lett. 100, (2008) T. Roger et al. Phys. Rev. C 79, (2009) 17/09/2015 T. Roger COMEX 5 9

10 MAYA: Limitations q 3 rd dimension from wires à Mostly stuck to binary reactions q Gassiplex electronics à Poor detection dynamics (~20) à Huge dead-time (>2 ms for 2000 pads) q 5 mm side pads (8 mm pitch) à Hard to reconstruct trajectories if range < few cm. beam 17/09/2015 T. Roger COMEX 5 10

11 Active Targets improvements q Improved detection dynamics à Use GET electronics: theoretical dynamical range of ~ digitized electronics à Possibility of pads polarization: reduces locally the amplification E.C. Pollaco et al., Physics Procedia 37, 1799 (2012) 17/09/2015 T. Roger COMEX 5 11

12 Active Targets improvements q Improved detection dynamics à Use GET electronics: theoretical dynamical range of ~ digitized electronics à Possibility of pads polarization: reduces locally the amplification à Use a semi-transparent mask to reduce the number of primary electrons J. Pancin et al., JINST 7, P01006 (2012) 17/09/2015 T. Roger COMEX 5 12

13 Active Targets improvements q Improved detection dynamics q Improved incoming beam intensity / heavy-z beams à Use a mask + field cage (Tactic-like) è E653 experiment: Angular distribution of fission fragment in transfer-induced fission using MAYA è Principle: use a 10 6 Hz 238 U 6A MeV in isobutane à Energy deposit ~ 1 PeV/s à Primary ions electric field: ~ 80 V/cm compared to drift field ~ 15V/cm 17/09/2015 T. Roger COMEX 5 13

14 Active Targets improvements q Improved detection dynamics q Improved incoming beam intensity / heavy-z beams à Use a mask + field cage (Tactic-like) C. Rodriguez-Tajes et al., NIM A 768, 179 (2014) 17/09/2015 T. Roger COMEX 5 14

15 Active Targets improvements q Improved detection dynamics q Improved incoming beam intensity / heavy-z beams à Use a mask + field cage (Tactic-like) à Use L2 triggers & CPU farms to reduce the number of accepted triggers 17/09/2015 T. Roger COMEX 5 15

16 Active Targets improvements: ACTAR TPC q Improved detection dynamics q Improved incoming beam intensity / heavy-z beams q Improved granularity: ACTAR TPC à pads, 2x2 mm² à GET electronics: digitized signals on each pad à Funded by ERC starting grant (G.F. Grinyer) è About 8 millions voxels! 17/09/2015 T. Roger COMEX 5 16

17 ACTAR TPC: Detector design q Drift region: à Demonstrator: 1 mm pitch single wire field cage à Final chamber: double wire cage with pitch > 2mm à Simulations ongoing Simulations: S. Damoy (GANIL) 17/09/2015 T. Roger COMEX 5 17

18 ACTAR TPC: Detector design q Drift region: à Demonstrator: 1 mm pitch single wire field cage à Final chamber: double wire cage with pitch > 2mm à Simulations ongoing q Amplification region: à Micromegas, 220 µm gap: OK for low pressure à Fast timing, robust, cost effective Y. Giomataris et al., NIM A 560, 405 (2006) 17/09/2015 T. Roger COMEX 5 18

19 ACTAR TPC: Detector design q Drift region: à Demonstrator: 1 mm pitch single wire field cage à Final chamber: double wire cage with pitch > 2mm à Simulations ongoing q Amplification region: à Micromegas, 220 µm gap: OK for low pressure à Fast timing, robust, cost effective q Segmented pad plane: à Very high density: 2x2 mm² (= 25 channels/cm²) à Total electronics channels, digitized (GET system) q Auxiliary detectors: à Telescopes for escaping particles (Si+Si or Si+CsI) à LaBr 3 or CeBr 3 for γ rays (SpecMAT ERC R. Raabe) 17/09/2015 T. Roger COMEX 5 19

20 ACTAR TPC: Versatile design q Design goal (1): Reconfigurable à Auxiliary detectors for particles and/or γ rays à Configurable Installation on any side à Depends on the kinematics of the experiment q Design goal (2): Versatility à Perform reaction and decay experiments à Two separate chambers will be designed q Design goal (3): Portability à Take advantage of unique beam production capabilities at each facility q Design goal (4): Synergies with other projects à SpecMAT ERC, PARIS and all potential users à GANIL/LISE future plans 17/09/2015 T. Roger COMEX 5 20

21 ACTAR TPC: ERC planning q ACTAR TPC ERC Project Planning à Experiments at GANIL/G3 (2016/2017), GANIL/LISE (2017), HIE-ISOLDE (2018) à Demonstrator experiments at IPNO (July 2015) 17/09/2015 T. Roger COMEX 5 21

22 ACTAR TPC: Demonstrator q 2048-channel pad plane 17/09/2015 T. Roger COMEX 5 22

23 ACTAR TPC: Demonstrator q 2048-channel pad plane à Used at IPNO in July 2015 (BACCHUS beam line) 17/09/2015 T. Roger COMEX 5 23

24 ACTAR TPC: Demonstrator q Two experiments performed at IPNO: α-clustering in light nuclei q 12 C(α,α ) inelastic scattering D. Suzuki et al., IPNO proposal q 6 Li(α,α) resonant scattering 17/09/2015 T. Roger COMEX 5 24

25 ACTAR TPC: Demonstrator q Two experiments performed at IPNO: α-clustering in light nuclei Beam 17/09/2015 T. Roger COMEX 5 25

26 ACTAR TPC: Future possible campaigns at LISE q Document on the exploitation of LISE in the horizon of 5 years currently written à Working groups constituted: shell evolution, collective modes, nuclear astrophysics à Presentation at the next GANIL SAC in October q Preliminary conclusions of the collective modes working group: à Possibility to combine ACTAR TPC and classic solid target + Château de Cristal setup à Study (α,α ) or (p,p ) and (γ*,γ) at the same time! è All collaborators are welcome! Contact: O. Sorlin, J. Gibelin, M. Vandebrouck 17/09/2015 T. Roger COMEX 5 26

27 MAYA / ACTAR TPC collaboration 17/09/2015 T. Roger COMEX 5 27