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The γ decay of the Hoyle and higher excitation energy states of 12 C

The γ decay of the Hoyle and higher excitation energy states of 12 C. N.S. Martorana Dipartimento di Fisica e Astronomia, «Ettore Majorana», Università degli Studi di Catania and INFN-LNS, Catania, Italy martorana@lns.infn.it On behalf of CHIMERA-NEWCHIM Collaboration.

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The γ decay of the Hoyle and higher excitation energy states of 12 C

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  1. The γdecay of the Hoyle and higher excitation energy states of 12C N.S. Martorana Dipartimento di Fisica e Astronomia, «Ettore Majorana», Università degli Studi di Catania and INFN-LNS, Catania, Italy martorana@lns.infn.it On behalf of CHIMERA-NEWCHIM Collaboration XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019

  2. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 Outline • Physical case (M. Freer H.O.U. Fynbo Progress in Particle and Nuclear Physics 78 (2014) 1–23) • 12C formation • Measured and evaluated γ decay widths • Experiment and results • Description of the method • The CHIMERA multidetector • γ ray detection • Kinematic coincidence • Preliminary results • Outlook • Conclusions

  3. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 J. Bishop PHD Thesis The synthesis of 12C in the helium burning phase proceeds through what is known as the triple α-process,where the first two α-particles fuse to form 8Be

  4. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 J. Bishop PHD Thesis The synthesis of 12C in the helium burning phase proceeds through what is known as the triple α-process,where the first two α-particles fuse to form 8Be The second step is the capture of a third α-particle (before 8Be decays back into two α-particles) to form 12C* followed by electromagnetic decay to the 12C ground state

  5. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 Hoyle recognized the need for a Jπ = 0+ state at 7.68 MeV, in order to account for the absolute abundance of 12C and the relative abundance of 12C and 16O (F. Hoyle, Astrophys. J. Suppl. Ser. 1 (1954) 12) 14N(d, α)12C reaction using a high resolution spectrometer  a state at 7.68 MeV was observed D.N.F. Dunbar et al., Phys. Rev. 92 (1953) 649 Subsequent measurements refined the energy of the state to 7.653 ± 0.008 MeV C.W. Cook et al., Phys. Rev. 107 (1957) 508

  6. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 J. Bishop PHD Thesis 12C ground state facilitated by the radiative branches: either two gamma-decay 0+2 + 0 +or e + e -pair production 0+ 0 + The energy and width of the Hoyle-state are among the key parameters needed for a precise determination of the reaction rate of the astrophysical 3α-reaction Γrad = Γγ + Γe+ e− B. Alshahrani et al EPJ Web 63, 01022 (2013) the γ decay branching ratio is fundamental for the production of carbon, being the only way to produce a carbon at the ground state

  7. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 Most of the measurementsdonelooking for coincidenceeventsα+ 12C (or p + 12C) following the methods of D. Chamberlin et al Phys. Rev. C 9 (1974) 69 butalso with the search for γ –γcoincidences A. W. Obstand W. J. BraithwaitePhys. Rev. C 13 (1976) 2033 B. Alshahrani et al EPJ Web of Conf. 63 01022 (2013) M. Tsumura et al Journ. of Phys. Conf. Ser. 569 (2014) 012051

  8. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 The most recent work to determine the Gpwidth was reported in ref. M. Chernykh et al PRL 105, 022501 (2010) with a reanalysis of previous electron inelastic scattering data and a low energy measurement performed at S-DALINAC, producing the result Gp= 62.3 ± 2.0 µeV Most of the measurementsdonelooking for coincidenceeventsα+ 12C (or p + 12C) following the methods of D. Chamberlin et al Phys. Rev. C 9 (1974) 69 butalso with the search for γ –γcoincidences A. W. Obstand W. J. BraithwaitePhys. Rev. C 13 (1976) 2033 B. Alshahrani et al EPJ Web of Conf. 63 01022 (2013) M. Tsumura et al Journ. of Phys. Conf. Ser. 569 (2014) 012051

  9. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 The accepteddecayprobability of Hoyle state Grad/G= 4.12±0.11 10-4wasobtainedasan average of manymeasurements (R.G. Markham et al Nucl. Phys. A 270 (1976) 489) Most of the measurementsdonelooking for coincidenceeventsα+ 12C (or p + 12C) following the methods of D. Chamberlin et al Phys. Rev. C 9 (1974) 69 butalso with the search for γ –γcoincidences A. W. Obstand W. J. BraithwaitePhys. Rev. C 13 (1976) 2033 B. Alshahrani et al EPJ Web of Conf. 63, 01022 (2013) M. Tsumura et al Journ. of Phys. Conf. Ser. 569 (2014) 012051

  10. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 At high temperatureT> 109 k also the 12C 3-levelat 9.64 MeVand 2+levelat 9.84 MeVgivesome contribution( C. Angulo et al., NPA 656 (1999) 3) The γ-decayprobability of suchlevelwasnevermeasured - there is only a lowerlevelprobability of the order of 10-7 (D. Chamberlin et al Phys.Rev.C10 (1974) 909) M. Tsumura et al Journ. of Phys. Conf. Ser. 569 (2014) 012051

  11. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 Upperlimitsgiven by D. Chamberlin et al Phys. Rev. C 10 (1974) 909 9.64 (3-) To improvesuchresult an experiment in Japan using12C beamdetected by the GrandRaidenSpectrometer and hydrogen target M. Tsumura et al Journ. of Phys. Conf. Ser. 569 (2014) 012051

  12. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 This kind of measurements is rather complex. For instance, in the case of direct measurement of γ-decay one must take into account also the angular correlation effects to correctly evaluate the efficiency due to the multi-polarity of the decay We need to measure in coincidenceallemittedparticlesprojectile - residual carbon nucleus & the γ-raycascade For the purpose to precisely investigate the decay mechanism of such states we conducted an experiment, at Laboratori Nazionali del Sud-Istituto Nazionale di Fisica Nucleare (INFN-LNS), using the reaction α + 12C at 64 MeV

  13. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 The basic idea is to join bothdetectionmethods in order to improve the sensitivity of the measurement : 4 foldcoincidencemeasurementusingthe CHIMERA detector α beam accelerated by CS @ LNS-INFN α + 12C(106 µg/cm2 ) @ 16 AMeV α + 12C  12C*+ α’ • Kinematiccoincidence with 12C recoil and inelastically scattered projectile particles • γ-raydetection 12C 3α α’ α’ 12C target 12C target α beam α beam

  14. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 The basic idea is to join bothdetectionmethods in order to improve the sensitivity of the measurement : 4 foldcoincidencemeasurementusingthe CHIMERA detector α beam accelerated by CS @ LNS-INFN α + 12C(106 µg/cm2 ) @ 16 AMeV α + 12C  12C*+ α’ Detection efficiency around 100% • Kinematiccoincidence with 12C recoil and inelastically scattered projectile particles • γ-raydetection 12C 3α α’ α’ 12C target 12C target α beam α beam

  15. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 CHIMERA (Charge Heavy Ion Mass and Energy Resolving Array) A . Pagano et al., Nucl. Phys. A, 734, (2004), 504 G. Cardella et al., NIM A, 799, (2015), 64 The target is centered at the center of the sphere

  16. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 CHIMERA (Charge Heavy Ion Mass and Energy Resolving Array) A . Pagano et al., Nucl. Phys. A, 734, (2004), 504 G. Cardella et al., NIM A, 799, (2015), 64

  17. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 CHIMERA (Charge Heavy Ion Mass and Energy Resolving Array) A . Pagano et al., Nucl. Phys. A, 734, (2004), 504 G. Cardella et al., NIM A, 799, (2015), 64 PSD – Si charge for particlesstopped in silicon ΔE-ToFmass for particlesstopped in silicon ΔE-Eisotopicidentification up to Z=12

  18. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 CHIMERA (Charge Heavy Ion Mass and Energy Resolving Array) A . Pagano et al., Nucl. Phys. A, 734, (2004), 504 G. Cardella et al., NIM A, 799, (2015), 64 ΔE-ToFmass for particlesstopped in silicon ΔE-Eisotopicidentification up to Z=12

  19. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 The CsI(Tl) of the CHIMERA spherehave a gooddetection efficiency for γ-rays G. Cardella et al., NIM A 799 64 (2015) M. Alderighi et al., NIM A 489 (2002) 257-265 Counts Qval(MeV) Eγ (MeV) Qval(MeV)

  20. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 The CsI(Tl) of the CHIMERA spherehave a gooddetection efficiency for γ-rays G. Cardella et al., NIM A 799 64 (2015) M. Alderighi et al., NIM A 489 (2002) 257-265 Counts Qval(MeV) Eγ (MeV) Qval(MeV) Angulardistributionfor the 2+level

  21. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 The CsI(Tl) of the CHIMERA spherehave a gooddetection efficiency for γ-rays N.S. Martorana et al., Phys. Lett. B 782 (2018) γ-rays efficiency around 10 MeV computed with Geant4 Efficiency computed with Geant4

  22. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 The CsI(Tl) of the CHIMERA spherehave a gooddetection efficiency for γ-rays N.S. Martorana et al., Phys. Lett. B 782 (2018) γ-rays efficiency around 10 MeV computed with Geant4

  23. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 • α + 12C • α + Au • α source • pulser Coincidence 12C spectrum Ene (MeV) Gs & 3.85 MeV from α+ 12c3He+13C (energy loss) Pedestal from pulser Elastic scattering on AU (energy loss) Ene (Ch.)

  24. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 Coincidence 12C spectrum Ene (MeV) Gs & 3.85 MeV from α+ 12c3He+13C (energy loss) α + 12C Pedestal from pulser α + Au Elastic scattering on AU (energy loss)

  25. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 8Be (2a) a 12C a 3He t d p α + 12C(106 µg/cm2 ) @ 16 AMeV accelerated by the CS ∆E – E to identify the α ∆E – E to identify the α E [Ch.] ∆E [Ch.] ToF [ns] E [Ch.] ∆E – E to identify the α E – ToF to identify the C nuclei We detect and identify in energybothscatteredα-particles ( by ∆E-E) and carbon (by time of flight)

  26. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 The minimum and maximum rings for the residual particle (12C) are due to the Δθon the ejectilering F. Favela et al 2018 J. Phys.: Conf. Ser. 1078 012010

  27. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 Kinematiccoincidence 12C - α 4.44 MeV . G.S. We see the ground state 12C and the first excited state of 4.44 MeV the other statescannot be seenbecausethey are covered by the background

  28. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 1 γ 4.44 Ene12C (MeV) GS 9.64 12.4 Hoyle Ea(MeV) With one gamma raywe are able to reduce the elasticpeak of more than 2 orders of magnitude and wesee the levelat 12.4 MeVthatwasimpossible to see in single spectra Kinematiccoincidence 12C - α 4.44 MeV . G.S.

  29. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 1 gamma 4.44 Ene12C (MeV) GS 9.63 12.4 Level 12.4 Q-val(MeV) Hoyle Ea(MeV) With one gamma raywe are able to reduce the elasticpeak of more than 2 orders of magnitude and wesee the levelat 12.4 MeVthatwasimpossible to see in single spectra Kinematiccoincidence 12C - α 4.44 MeV . G.S.

  30. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 4.44 4.44 Ene12C (MeV) GS 9.64 9.64 12.4 Level 12.4 12.4 Hoyle Q-val (MeV) Hoyle Q-val (MeV) Ea(MeV) 1 γ 2 γ Ene12C (MeV) Ea(MeV)

  31. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 4.44 4.44 Ene12C (MeV) GS 9.64 9.64 12.4 12.4 Hoyle Hoyle Q-val (MeV) Ea(MeV) 1 γ Switchingon a twoγraycoincidencewereduce the 4.44 MeVcontributionagainof more than 2 order of magnitude. The Hoylestate is nowclean 2 γ Ene12C (MeV) Ea(MeV)

  32. 105° CongressoNazionaledellaSocietàItaliana di Fisica , L’Aquila 23 - 27 Settembre, 2019 We alsomeasured the 3αchanneldecay 1 γ 2 γ Q-val (MeV) Q-val (MeV) Q-val (MeV)

  33. 105° CongressoNazionaledellaSocietàItaliana di Fisica , L’Aquila 23 - 27 Settembre, 2019 We alsomeasured the 3αchanneldecay 1 γ 2 γ Q-val (MeV) Data analysis still on going to evaluate the efficiency performing also simulations 17-21 July experiment performed to increase the statistics we should be able to improve the knowledge also for the Gg/Gfor the 9.64 3- level Q-val (MeV) Q-val (MeV)

  34. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 Conclusions • Experiment performed to study the decay of the Hoyle state and higher excitation energy states • We used both methods ( gamma and particles detection) • The CHIMERA multidetector • γray detection • Kinematic coincidence • Preliminary results Outlook • Simulations to evaluate the detection efficiency • Data analysis on the experiment (17 – 21 July) in order to increase the statistics

  35. G. Cardella1,F. Favela1, N.S. Martorana 2,3, L. Acosta 4,1, L. Auditore 5,1, A. Camaiani6, E. De Filippo1, S. De Luca 5,1, N. Gelli 6,E. Geraci 1,3 ,B. Gnoffo1,2, D.J. Marín-Lámbarri4, G. Lanzalone 3,8, C. Maiolino3, A. Nannini 6, A. Pagano1, E.V. Pagano3 , M. Papa1, S. Pirrone1, G. Politi 1,2, E. Pollacco8, L. Quattrocchi 5,1, F. Rizzo 2,3, P. Russotto3, A. Trifirò5,1, and M. Trimarchi5,1 1 INFN sezione di Catania, Italy 2 Dipartimento di Fisica e Astronomia «Ettore Majorana», Università di Catania, Italy 3 INFN-LNS, Catania, Italy 4Instituto de Física, UniversidadNacionalAutónoma de México 5 Dipartimento di Scienze MIFT, Università di Messina, Italy 6 INFN sezione di Firenze and Dip. di Fisica Università di Firenze, Italy 7Facoltà di Ingegneria e Architettura, Università Kore, Italy 8 CEA IRFU Saclay, Gifsur Yvette, France Thankyou for yourattention

  36. XVII International Meeting on “Selected Topics in Nuclear and Atomic Physics” Fiera di Primiero, Sept 29 - Oct 4, 2019 FRAISE the new FRAgmentIn- FligthSEparator of INFN-LNS The project of an upgrade of the LNS-INFN Superconducting Cyclotron, leading to an increase of the power of available primary beams, will open new perspectives for the production of RIBs upgrade opens up a rather new scenario: ≈ 2kW primary beam! Also a revision and improvement of the diagnostic systems will be needed to measure the intensity and the profile of the RIBs cocktail along the lines, in order to perform an optimal transport towards the target stations N.S. Martorana

  37. Sigma =0.54 MeV Efficiency (E>3 MeV)=24% (due to some not working det.) Eg(MeVee) We recently upgraded our CsI(Tl) electronics with the new fully digital GET electronics From the decay of 4.44 12C level (sum of all working chimera detector)

  38. 105° CongressoNazionaledellaSocietàItaliana di Fisica , L’Aquila 23 - 27 Settembre, 2019 Kinematiccoincidence 12C - α 1 γ 2 γ Example of kinematic coincidence of alpha particles and 12C recoils. The ground state and the 4.44 MeV level can be seen. Q-val spectrum (MeV) Data analysis still on going to evaluate the efficiency performing also simulations Q-val spectrum (MeV)

  39. CsI(Tl) calibration Linear calibration for protons, obtained for a telescope of the CHIMERA sphere

  40. CsI(Tl) calibration 30° ≤θ≤78 ° Background can be evaluated collecting the same events, triggered by the detection of protons elastically scattered Q-value spectrum for the p + 12C reaction.

  41. We verified that we can extract angular distributions from such events  very useful to understand the multipolarity of the emitted γ-rays obtaining information about the spin of the observed resonance. See also G. Cardella et al, Nuclear Instrument and Methods in Physics Research A799 (2015) 64-69

  42. CsI(Tl) identification The blue spectrum corresponds to γ-rays correctly identified while the red one corresponds to spurious coincidences

  43. CsI(Tl) identification Sketch of the slow gate timing. The "event accepted“ signal, produced by the trigger, enables one RF signal. This signal is used as reference time to generate all gates. The dashed region shows the slow integration region of a signal, produced by a good coincidence. One can note the difference with the charge, integrated with the same gate, for a signal produced in a different burst (dashed signal that corresponds to spurious coincidence) M. Alderighi et al., NIM A 489, (2002), 257-265

  44. CHIMERA MULTIDETECTOR

  45. CHIMERA MULTIDETECTOR

  46. CHIMERA MULTIDETECTOR

  47. CHIMERA (Charge Heavy Ion Mass and Energy Resolving Array) A . Pagano et al., Nucl. Phys, A, 734, (2004), 504

  48. M. Alderighi et al., NIM A 489, (2002), 257-265 By fitting the observed distribution of the events, corresponding to spurious coincidences with different beam bursts, one can determine the dependence of the slow component on the time jitter of the signal. Spurious coincidences generated by cosmic rays obviously generate a noise in the fast-slow scatter plots. In order to evaluate such random contribution, one can simply integrate a region of the fast-slow plot far from good identified particles..

  49. GEANT4 simulations and folding S. Agostinelli et al., Nuclear Instruments and Methods in Physics Research Section A vol. 506, no. 3, (2003) D. Kresan et al., Journal of Physics: Conference Series, vol. 523, no. 1, (2014) Geometry of the CHIMERA multidetector as used for the GEANT4 simulations. Also the Si detectors of the FARCOS array, placed after the CHIMERA multidetector sphere are visible γ-rays energy spectrum obtained with GEANT4 θ ≈ 30 °

  50. Coinc 1 gamma 4.44 G.S. 9.63 7.65 12.7 Coinc 2 gamma 7.65 4.44 9.63 12.7 Alfa- 1 gamma target 13C

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