Systematics of the power law parameter and minimum angular momenta for fragment production

Trautmann, W.; Milkau, Udo; Lynen, U.; Pochodzalla, J.

doi:10.1007/bf01283202

Cited by 18 publications

(5 citation statements)

References 48 publications

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“…a saturation of the production cross sections for intermediate-mass fragments at bombarding energies in excess of several GeV, has been observed [47][48][49]. It is also an experimentally established fact that the elemental distributions change very little at high bombarding energies [50,51]. This suggests that the cross sections for the formation of highly excited spectator nuclei may be rather weak functions of the bombarding energy in the GeV range.…”

Section: Fragmentation At High Bombarding Energiesmentioning

confidence: 93%

Universality of spectator fragmentation at relativistic bombarding energies

et al. 1996

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Multi-fragment decays of 129 Xe, 197 Au, and 238 U projectiles in collisions with Be, C, Al, Cu, In, Au, and U targets at energies between E/A = 400 MeV and 1000 MeV have been studied with the ALADIN forward-spectrometer at SIS. By adding an array of 84 SiCsI(Tl) telescopes the solid-angle coverage of the setup was extended to θ lab = 16 • . This permitted the complete detection of fragments from the projectile-spectator source.The dominant feature of the systematic set of data is the Z bound universality that is obeyed by the fragment multiplicities and correlations. These observables are invariant with respect to the entrance channel if plotted as a function of Z bound , where Z bound is the sum of the atomic numbers Z i of all projectile fragments with Z i ≥ 2. No significant dependence on the bombarding energy nor on the target mass is observed. The dependence of the fragment multiplicity on the projectile mass follows a linear scaling law.The reasons for and the limits of the observed universality of spectator fragmentation are explored within the realm of the available data and with model studies. It is found that the universal properties should persist up to much higher bombarding energies than explored in this work and that they are consistent with universal features exhibited by the intranuclear cascade and statistical multifragmentation models.

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Section: Fragmentation At High Bombarding Energiesmentioning

confidence: 93%

Universality of spectator fragmentation at relativistic bombarding energies

et al. 1996

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“…The spin values resulting from this analysis turn out to be two to three times the critical angular momenta gc~t which were suggested as lower limits for fragment emission [23]. In view of the large entrance-channel angular momenta, reaching up to about 1000 h for the most peripheral collisions, they are rather moderate.…”

Section: E~ot_m =Au(rco)z/2; L=jco; R=r(lo8-a)/108mentioning

confidence: 95%

“…The thermal velocity components were calculated from a Maxwell-Boltzmann distribution r = 1.55 is lower than typical values deduced for reactions with lighter projectiles [23], i.e. the yields of heavier fragments are relatively larger.…”

Section: Emission From Rotating Systemsmentioning

confidence: 99%

Inclusive fragment production in84Kr +197Au atE/A=35 MeV

Milkau

Begemann-Blaich

Eckert

et al. 1993

Z. Physik A - Hadrons and Nuclei

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Abstract. Inclusive cross sections of intermediate mass fragments from the reaction 84Kr-~-I97Au at ElA = 35 MeV were measured over the range 8 ~ < Olab < 70 ~ with a low detection threshold. A moving-source parameterization was used to fit the double-differential cross sections. The integrated cross section for fragment production exceeds the total reaction cross section thus indicating a large probability for multi-fragment processes. The deduced large temperature parameters can be explained by assuming emission from a rotating source. From the comparison to reactions with 12C and 4~ projectiles at E/A = 30 MeV a systematics of inclusive fragment production as a function of the projectile mass is obtained. 25.70.Lm; 25.70.Mn; 25.70.Pq to 3.6 GeV, they seem to be associated with the larger IMF multiplicities [ 11 ]. PACS:In this work the systematics of the inclusive IMF production is extended to heavier projectiles. We report cross sections for the reaction at E/A = 35 MeV which were measured with a low detection threshold over a large range of angles. The atomic number of the observed fragments extends from Z = 3 up to Z = 36. Fragments up to Z = 24 were included in the moving-source analysis of the measured double-differential cross sections. By comparing to data for the reactions 12C "q-197Au[12] and 4~ + !97Au [6], both at E/A = 30 MeV, the role of the projectile mass in this energy regime is investigated. This measurement also complements the numerous exclusive studies of the 84Kr + 197Au reaction which were conducted in order to discern the dominant mechanisms of fragment production [13][14][15][16][17].

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“…Third, power law distributions are typical for "destructive" phenomena, which range from insurance events such as earthquakes, fires, or avalanches, to distribution of the mass of asteroids (created by destructive collisions) and fragments in heavy ion collisions (see Clauset et al 2009;Trautmann et al 1993). Therefore, the severity S and frequency F(S) are plotted in a double logarithmic diagram in Figure 1, and the power-law distribution is a straight line with log 10 (F) = const − (λ • log 10 (S)).…”

Section: Active Operational Risk Management and The Domains Of The "Umentioning

confidence: 99%

Active Management of Operational Risk in the Regimes of the “Unknown”: What Can Machine Learning or Heuristics Deliver?

Milkau

Bott

2018

Risks

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Abstract:Advanced machine learning has achieved extraordinary success in recent years. "Active" operational risk beyond ex post analysis of measured-data machine learning could provide help beyond the regime of traditional statistical analysis when it comes to the "known unknown" or even the "unknown unknown." While machine learning has been tested successfully in the regime of the "known," heuristics typically provide better results for an active operational risk management (in the sense of forecasting). However, precursors in existing data can open a chance for machine learning to provide early warnings even for the regime of the "unknown unknown."

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Systematics of the power law parameter and minimum angular momenta for fragment production

Cited by 18 publications

References 48 publications

Universality of spectator fragmentation at relativistic bombarding energies

Universality of spectator fragmentation at relativistic bombarding energies

Inclusive fragment production in84Kr +197Au atE/A=35 MeV

Active Management of Operational Risk in the Regimes of the “Unknown”: What Can Machine Learning or Heuristics Deliver?

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