Evidence for simultaneous breakup in reactions with relativistic α-projectiles

Lips, V.; Barth, Rolf F.; Oeschler, H.; Avdeyev, S. P.; Karnaukhov, V.A.; Kuznetsov, W.D.; Petrov, L.A.; Bochkarev, O.V.; Chulkov, L. V.; Kuzmin, E. A.; Karcz, W.; Neubert, W.; Norbeck, E.; Gross, D. H. E.

doi:10.1016/0370-2693(94)91357-9

Cited by 22 publications

(5 citation statements)

References 20 publications

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“…Primary fragment are hot and their de excitation is considered by SMM [4] to get the final distributions of cold IMF's in two breakup volume conditions (freeze-out volume V = 3V 0 and freeze-out volume V = 5V 0 ). For each fragment in a given event the starting time to move along Coulomb trajectory has been randomly chosen according to the decay probability of the system: P(t) ~exp(−t/τ).…”

Section: Results Of Measurementsmentioning

confidence: 99%

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From Sequential Processes to Multifragmentation in Proton Reactions with Gold

Avdeyev¹,

Karnaukhov²,

Oeschler³

et al. 2013

JMP

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The distribution of relative angles between the intermediate mass fragments has been measured and analyzed for thermal multifragmentation in p + Au collisions at 2.1, 3.6 and 8.1 GeV. The analysis has been done on an event by event basis. The multibody Coulomb trajectory calculations of all charged particles have been performed starting with the initial break-up conditions given by the combined model with the revised intranuclear cascade (INC) followed by the statistical multifragmentation model. The measured correlation function was compared with the calculated one to find the actual time scale of the intermediate mass fragment (IMF) emission. It found transition from sequential evaporation for p(2.1 GeV) + Au to simultaneous multibody decay of a hot and expanded nuclear system in case of p(8.1 GeV) + Au.

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Section: Results Of Measurementsmentioning

confidence: 99%

“…The first measurements of the time scale for the thermal multifragmentation were performed for 4 He + Au collisions at 14.6 GeV by analyzing the IMF-IMF relative angle correlation [3,4]. It was found that  em is less than 75 fm·c He with the gold target [6].…”

Section: Introductionmentioning

confidence: 99%

From Sequential Processes to Multifragmentation in Proton Reactions with Gold

Avdeyev¹,

Karnaukhov²,

Oeschler³

et al. 2013

JMP

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“…At excitation energies below 1 MeV unit −1 , dominant de-excitation processes are binary fission and evaporation of light particles (n, p and α). For higher excitation energies, there is an increasing probability for production of intermediate-mass fragments (IMFs) [1,2] and events ending with three and more fragments [3], [7][8][9][10]. The field of fragmentation processes both in heavy-ion collisions and in light-ion-induced reactions is of interest due to its importance for understanding the underlying reaction mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, in the light-ion-induced reactions, residual nuclei with a wide mass and excitation energy distribution are formed. Decay of the target residue is a subject of intensive theoretical and experimental studies in the literature [2,3], [7][8][9]. The type of the fragment emission mechanism strongly affects the timescale for heavy and IMF emission.…”

Section: Introductionmentioning

confidence: 99%

On the determination of the time-scale of three-fragment emission in the 12.7 GeV⁴He+²³⁸U reaction using the polycarbonate track detector Makrofol

et al. 2011

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The timescale for emission of three fragments (Z 8) in the 12.7 GeV 4 He + 238 U reaction has been studied using a sandwich configuration of the Makrofol polycarbonate track detector. In events with varying multiplicity of heavy fragments (Z > 20), the differences of the correlation functions for relative angle and relative velocity between pairs of fragments have been studied in order to determine the fragment emission timescale. A sequential decay mechanism for the excited residual nuclei was found to be consistent with experimental data. It was determined that the fragment emission time decreased with decreasing multiplicity of heavy fragments from 1200 ± 80 fm c −1 for events with two heavy fragments to 400 ± 50 fm c −1 for events with one heavy fragment.

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“…At high bombarding energy, E/A ) 100 MeV, the fragments appear to be emitted on the very short time scale implied by a prompt multi&agment disassembly of heated and expanded nuclear systems [2,3]. At low bombarding energy, E/A & 20 MeV, standard compound nucleus decay accounts for much of the fragment yield following either complete or incomplete fusion reactions [4 -6].…”

mentioning

confidence: 99%

Space-time characteristics of fragment emission in theE/A=30 MeVXe129+
Bowman¹,
Colonna²,
Friedman³
et al. 1995
Phys. Rev. C
25
0
4
0
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Intermediate-mass-fragment emission has been studied in central E/A = 30 MeV Xe + " 'Cu reactions. The measured fragment multiplicities, reduced-velocity correlation functions, and emission velocities have been compared with schematic three-body trajectory calculations and with three statistical models with input based upon a dynamical BNV code. The statistical models which include expansion either explicitly or implicitly are able to generate a sufBcient number of fragments. The three-body trajectory calculations indicate a mean emission time of = 200 fm/c, consistent with sequential decay. Dynamical expanding-emitting source calculations predict a similar time scale for fragment emission and give satisfactory agreement with the experimental correlation functions if the experimental angular distributions are incorporated into the model. The Berlin multifragmentation model gives good agreement with the experimental charge distributions, and, depending upon the choice of radius parameter, can provide agreement with either the correlation functions or the fragment emission velocities, but not with both simultaneously. Although an overall good agreement is obtained in the statistical model comparisons, even in the most violent collisions the angular distributions and fragment emission velocities are incompatible with completely equilibrated decay from a single source. PACS uumber(s): 25.70.Pq I. INTR.C)DU CTI(3N Studies of IMF (intermediate mass fragment, 3 & Z ( 20) emission [1] have provided a wealth of information about the space-time extent of excited nuclear systems. At high bombarding energy, E/A ) 100 MeV, the fragments appear to be emitted on the very short time scale implied by a prompt multi&agment disassembly of heated and expanded nuclear systems [2,3]. At low bombarding energy, E/A & 20 MeV, standard compound nucleus decay accounts for much of the fragment yield following either complete or incomplete fusion reactions [4 -6]. To gain a systematic understanding of the interaction between complex nuclei it is important to characterize the intermediate bombarding energy regime, where the fragment emission time scale changes from sequential to simultaneous [7,8], and nuclear expansion begins to occur [9,10].Observables which have been employed to infer the spatial and temporal extensions of fragmentation sources are &agment yields, &agment-&agment reduced-velocity correlation functions, and emission velocities of emitted fragments.The IMF yields calculated with statistical emission models are strongly dependent on the density of the emitting system [11 -14]. Comparisons of experimental data with model predictions have shown that nuclear expansion is needed to reproduce the observed fragment multiplicities and charge distributions, even at bombarding energies as low as E/A = 35 MeV [13]. The fragment emission time scale, as determined from fragmentfragment correlations, is a direct measure of the spacetime extent of the source [2,3,7,8, 15 -26]. The fragment emission velocities are sensitive to an expansion ...

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Evidence for simultaneous breakup in reactions with relativistic α-projectiles

Cited by 22 publications

References 20 publications

From Sequential Processes to Multifragmentation in Proton Reactions with Gold

From Sequential Processes to Multifragmentation in Proton Reactions with Gold

On the determination of the time-scale of three-fragment emission in the 12.7 GeV⁴He+²³⁸U reaction using the polycarbonate track detector Makrofol

Space-time characteristics of fragment emission in theE/A=30 MeVXe129+
Bowman¹,
Colonna²,
Friedman³
et al. 1995
Phys. Rev. C
25
0
4
0
View full text Add to dashboard Cite

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Evidence for simultaneous breakup in reactions with relativistic α-projectiles

Cited by 22 publications

References 20 publications

From Sequential Processes to Multifragmentation in Proton Reactions with Gold

From Sequential Processes to Multifragmentation in Proton Reactions with Gold

On the determination of the time-scale of three-fragment emission in the 12.7 GeV4He+238U reaction using the polycarbonate track detector Makrofol

Space-time characteristics of fragment emission in theE/A=30 MeVXe129+Bowman1, Colonna2, Friedman3 et al. 1995Phys. Rev. C25040View full textAdd to dashboardCite

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On the determination of the time-scale of three-fragment emission in the 12.7 GeV⁴He+²³⁸U reaction using the polycarbonate track detector Makrofol

Space-time characteristics of fragment emission in theE/A=30 MeVXe129+
Bowman¹,
Colonna²,
Friedman³
et al. 1995
Phys. Rev. C
25
0
4
0
View full text Add to dashboard Cite