INDRA (“Identification de Noyaux et Détection avec Résolutions Accrues”) is a 4pi multidetector of charged particles in use since 1993 for the study of nuclear reaction dynamics and the thermodynamics of hot nuclei, with the ultimate goal of determining the equation of state of nuclear matter which is an essential ingredient for understanding either the structure of exotic nuclei or astrophysical phenomena such as neutron stars and type II supernova explosions.
INDRA is a highly segmented detector for light charged particles and fragments composed of 336 independent detection modules (telescopes) positioned in axially-symmetric rings covering polar angles from 2 to 176 degrees. It covers geometrically 90% of the 4pi solid angle around the target and has very low identification thresholds (~1 A MeV), achieved by using as first stage of the telescopes ionization chambers operated with low pressure C3F8 gas. Residual energies are measured by a combination of silicon (150 or 300 µm thick) and/or caesium iodide (5 to 14 cm in length) detectors as second and/or third stage of the telescopes, depending on polar angle. At very forward angles (2 to 3 degrees) the original ring of phoswich scintillators (NE102/NE115) used in the first 3 campaigns of experiments was replaced in 1998 by 12 Si(300µm)-CsI(14cm) telescopes.
For more details on the array and its detectors, see: J. Pouthas et al., Nuclear Instruments and Methods in Physics Research A357, 418 (1995) : http://linkinghub.elsevier.com/retrieve/pii/0168900294015430
Detector signal treatment is performed through specifically designed modules, most of which are in the VXI standard. This standard allowed to considerably reduce the number of electronic modules required by the 640 detectors by regrouping many functions in the same module. Charge preamplifiers for ionization chambers and silicon detectors are mounted in the vacuum chamber, as close as possible to the detectors, while all the electronics racks are in the beam cave, the VXI standard providing full remote control including multiplexing of analogic and logic signals to be visualized in the acquisition room, while experiments are running. The innovative “asynchronous” trigger system allows to record reactions from low to very high multiplicities (from peripheral to central collisions) with low dead time and very little bias. The custom-made INDRA Selecteur VXI trigger module is also extremely flexible, allowing easy coupling with other detectors and acquisition systems such as Chimera (1997), VAMOS (2007), and now FAZIA (2018-?).
For more details on the electronics of the INDRA array, see: J. Pouthas et al., Nuclear Instruments and Methods in Physics Research A369, 222 (1996) : http://linkinghub.elsevier.com/retrieve/pii/0168900295007709
Unit charge resolution up to Z~54 is achieved over a large dynamic range in energy (5000 to 1 for silicon detectors) for fragments punching through the silicon detectors. Heavier fragments (up to lead) stopping in the silicon detectors can be identified with resolution of a few Z units from their energy loss in the ionization chamber, with low identification thresholds of ~1 AMeV. Light fragments punching through to the CsI detectors can be isotopically identified using the fast and slow components of the scintillator light output up to Z=5 in the best cases. The gradual replacement of the 300µm Si by 150µm thick detectors (from 2001 onwards) allows for certain telescopes (up to 45 degrees polar angle) to achieve isotopic resolution for fragments up to Z=8; in addition to this, for some experimental campaigns mass resolution up to Z=6 has also been possible even in the 300µm thick Si-CsI telescopes. Further improvement even for existing data is possible (see O. Lopez et al., “Improving isotopic identification with INDRA Silicon–CsI(Tl) telescopes”, Nuclear Inst. and Methods in Physics Research, A 884 (2018) 140–149).
During the first 10 years of operation, experiments with INDRA were run in campaigns using many weeks of beam time in order to optimise the (large) effort of data reduction required to reconstruct, identify and calibrate the particles in each recorded collision. In more recent years, both advances in computer power & software tools, and a reduction in available beam-time, have meant a focus on more individual experiments.
The following non-exhaustive list gives some of the major works of the collaboration, sorted according to the most recent data they contain (i.e. under “4th campaign” are works based on data from that campaign, but also potentially from the previous campaigns)
1st campaign – 1993 – GANIL
“Vaporization events from dissipative binary collisions”, M.F. Rivet, A. Chbihi, B. Borderie, et al., Physics Letters B 388 (1996) 219; “Thermal and chemical equilibrium for vaporizing sources”, B. Borderie et al. (INDRA collaboration), Eur. Phys. J. A 6, 197–202 (1999)
“Onset of midvelocity emissions in symmetric heavy ion reactions”, E. Plagnol et al (INDRA collaboration), Physical Review C 61 (1999) 014606; “Mass scaling of reaction mechanisms in intermediate energy heavy ion collisions”, V. Métivier et al (INDRA collaboration), Nuclear Physics A 672 (2000) 357; “Study of intermediate velocity products in the Ar+Ni collisions between 52 and 95 A.MeV”, T. Lefort et al., Nuclear Physics A 662 (2000) 397–422
“A hot expanding source in 50 A MeV Xe + Sn central reactions”, N. Marie et al., Physics Letters B 391(1997) 15-21; “Multifragmentation of a very heavy nuclear system (II): bulk properties and spinodal decomposition”, J. D. Frankland et al. (INDRA collaboration), Nuclear Physics A 689 (2001) 940–964; “Evidence for Spinodal Decomposition in Nuclear Multifragmentation”, B. Borderie et al. (INDRA collaboration), Physical Review Letters 86 (2001) 3253; “On the reliability of negative heat capacity measurements”, M. D’Agostino et al, Nuclear Physics A 699 (2002) 795–818
“Characteristics of the fragments produced in central collisions of 129Xe+natSn from 32A to 50A MeV”, S. Hudan et al, Physical Review C 67 (2003) 064613; “Freeze-out properties of multifragmentation events”, S. Piantelli et al (INDRA collaboration), Nuclear Physics A 809 (2008) 111–128; “Constrained caloric curves and phase transition for hot nuclei”, B.Borderie et al (INDRA collaboration), Physics Letters B 723 (2013) 140–144
“Universal Fluctuations in Heavy-Ion Collisions in the Fermi Energy Domain”, R. Botet, M. Ploszajczak, A. Chbihi, B. Borderie, D. Durand and J. Frankland, Physical Review Letters 86 (2001) 3514
2nd campaign – 1994 – GANIL
“Dynamical effects in multifragmentation at intermediate energies”, J. Colin et al. (INDRA Collaboration), Physical Review C 67 (2003) 064603
“Multifragmentation process for different mass asymmetry in the entrance channel around the Fermi energy”, N. Bellaize et al. (INDRA collaboration), Nuclear Physics A 709 (2002) 367–391
“Isospin diffusion in 58Ni-induced reactions at intermediate energies”, E. Galichet et al, Physical Review C 79 (2009) 064614
3rd campaign – 1997 – GANIL
“Multi-particle correlation function to study short-lived nuclei”, F. Grenier et al (INDRA collaboration), Nuclear Physics A 811 (2008) 233–243
“Multifragmentation threshold in 93Nb+ natMg collisions at 30 MeV/nucleon”, L. Manduci et al (INDRA and CHIMERA collaborations), Nuclear Physics A 811 (2008) 93–106
4th campaign – 1998/9 – GSI
“Model-independent tracking of criticality signals in nuclear multifragmentation data”, J.D Frankland et al. (INDRA and ALADIN collaborations), Physical Review C 71 (2005) 034607; “Yield scaling, size hierarchy and fluctuations of observables in fragmentation of excited heavy nuclei”, N. Le Neindre et al (INDRA and ALADIN collaborations), Nuclear Physics A 795 (2007) 47–69; “Bimodal Behavior of the Heaviest Fragment Distribution in Projectile Fragmentation”, E. Bonnet et al. (INDRA and ALADIN collaborations), Physical Review Letters 103 (2009) 072701
“INDRA@GSI: collective flow in Au + Au collisions”, J. Lukasik et al (INDRA and ALADIN collaborations), Progress in Particle and Nuclear Physics 53 (2004) 77–80; “Transition from participant to spectator fragmentation in Au+Au reactions between 60A and 150A MeV”, K. Zbiri et al (INDRA and ALADIN collaborations), Physical Review C 75 (2007) 034612
5th campaign – 2001 – GANIL
“Study of Nuclear Stopping in Central Collisions at Intermediate Energies”, G. Lehaut et al. (INDRA and ALADIN collaborations), Physical Review 104 (2010) 232701; “In-medium effects for nuclear matter in the Fermi-energy domain”, O. Lopez et al (INDRA collaboration), Physical Review C 90 (2014) 064602
“Nuclear Multifragmentation Time Scale and Fluctuations of the Largest Fragment Size”, D. Gruyer et al. (INDRA collaboration), Physical Review Letters 110 (2013) 172701
“Coulomb chronometry to probe the decay mechanism of hot nuclei”, D. Gruyer et al. (INDRA collaboration), Physical Review C 92 (2015) 064606
“Light charged clusters emitted in 32 MeV/nucleon 136,124Xe + 124,112Sn reactions: Chemical equilibrium and production of 3He and 6He”, R. Bougault et al (INDRA collaboration), Physical Review C 97 (2018), 024612
“Phase transition dynamics for hot nuclei”, B. Borderie et al. (INDRA collaboration), Physics Letters B 782 (2018) 291–296
2003-2005: E416 & E416a Measure of fission times by crystal blocking technique
“Fission Time Measurements: A New Probe into Superheavy Element Stability”, M. Morjean et al, Physical Review Letters 101 (2008) 072701
2006: E475S – Isospin effects on compound nuclear decay
“Decay of excited nuclei produced in 78,82Kr+40Ca reactions at 5.5 MeV/nucleon”, G. Ademard et al., Physical Review C 83 (2011) 054619
2007: INDRA-VAMOS campaign
“Signals of Bose Einstein condensation and Fermi quenching in the decay of hot nuclear systems”, P. Marini et al. (INDRA collaboration), Physics Letters B 756 (2016) 194
2011: E613 – Entrance channel mass asymmetry effect on phase diagram trajectories
“Comparison of radial flow effects on partitions of multifragmenting sources formed in symmetric and asymmetric central collisions”, J.D. Frankland, D. Gruyer, E. Bonnet & A. Chbihi (INDRA/E613 collaboration), EPJ Web of Conferences 88 (2015) 00009
Scientific coordinator: John Frankland – email@example.com
More information: http://indra.in2p3.fr/spip/