Fusion Hindrance and Pauli Blocking in 58Ni + 64Ni

58Ni +64Ni is the first case where the influence of positive Q-value transfer channels on sub-barrier fusion was evidenced, in a very well known experiment by Beckerman et al., by comparing with the two systems 58Ni + 58Ni and 64Ni+64Ni. Subsequent measurements on 64Ni + 64Ni showed that fusion hindrance is clearly present in this case. On the other hand, no indication of hindrance can be observed for 58Ni + 64Ni down to the measured level of 0.1 mb. In the present experiment the excitation function has been extended by two orders of magnitude downward. The cross sections for 58Ni + 64Ni continue decreasing very smoothly below the barrier, down to '1 µb. The logarithmic slope of the excitation function increases slowly, showing a tendency to saturate at the lowest energies. No maximum of the astrophysical S -factor is observed. Coupled-channels (CC) calculations using a Woods-Saxon potential and includinginelastic excitations only, underestimate the sub-barrier cross sections by a large amount. Good agreement is found by adding two-neutron transfer couplings to a schematical level. This behaviour is quite different from what already observed for 64Ni+ 64Ni (no positive Q-value transfer channels available), where a clear low-energy maximum of the S -factorappears, and whose excitation function is overestimated by a standard Woods-Saxon CC calculation. No hindrance effect is observed in 58Ni+ 64Ni in the measured energy range. This trend at deep sub-barrier energies reinforces the recent suggestion that the availability of several states following transfer with Q>0, effectively counterbalances the Pauli repulsion that, in general, is predicted to reduce tunneling probability inside the Coulomb barrier

Jet reconstruction with machine learning methods

Rekonstrukcija cijelog mlaza u modernoj fizici problematična je zbog detektorskih efekata i nepotpunog poznavanja hadronizacije. Rekonstrukcija se temelji na simulacijama događaja i simuliranom odazivu detektora iz kojeg se onda određuje efikasnost rekonstrukcije pojedinog kanala koji se razmatra. Efikasnost se tada uračunava u mjerene podatke stvarnih događaja, za koje se pretpostavlja da prate iste distribucije kao i simulirani događaji. U ovom radu bi se napravio novi, pojednostavljeni simulator mlazova koji bi usmjeravali na N x N polje koje predstavlja detektor. U svakom elementu polja, za pojednostavljeni snop, zapisao bi se četverovektor impulsa i energije te bi cjelokupno polje predstavljalo fizikalni snop. Realna slika snopa tad bi se dobila uvođenjem detektorskih efekata na polje. Konačno, vidjet ćemo je li pomoću metoda strojnog učenja moguće rekonstruirati fizikalni snop iz njegove realne slike, te je li efikasnost takve rekonstrukcije usporediva s efikasnostima modernih metoda.Jet reconstruction in modern physics poses problems due to detector effects and incomplete knowledge of hadronisation. The reconstruction is based on simulated events and simulated responses of the detector from which the efficiency of the reconstruction in individual channels is determined. Efficiency is then included in the measurement data of real events, which is assumed to follow the same distributions as the simulated events. In this paper, we generate a new simplified jet simulator that would be directed onto the N x N field represented by the detector. In each element of the field, for a simplified beam, an energy-momentum four-vector would be written and the whole field would represent a physical beam. Realistic image of the beam would then be obtained by introducing detector effects on the field. Finally, we’ll see if it is possible to reconstruct the physical jet from its images by using machine learning method and whether the efficiency of such reconstruction is comparable to the efficiencies of modern methods

Jet reconstruction with machine learning methods

Rekonstrukcija cijelog mlaza u modernoj fizici problematična je zbog detektorskih efekata i nepotpunog poznavanja hadronizacije. Rekonstrukcija se temelji na simulacijama događaja i simuliranom odazivu detektora iz kojeg se onda određuje efikasnost rekonstrukcije pojedinog kanala koji se razmatra. Efikasnost se tada uračunava u mjerene podatke stvarnih događaja, za koje se pretpostavlja da prate iste distribucije kao i simulirani događaji. U ovom radu bi se napravio novi, pojednostavljeni simulator mlazova koji bi usmjeravali na N x N polje koje predstavlja detektor. U svakom elementu polja, za pojednostavljeni snop, zapisao bi se četverovektor impulsa i energije te bi cjelokupno polje predstavljalo fizikalni snop. Realna slika snopa tad bi se dobila uvođenjem detektorskih efekata na polje. Konačno, vidjet ćemo je li pomoću metoda strojnog učenja moguće rekonstruirati fizikalni snop iz njegove realne slike, te je li efikasnost takve rekonstrukcije usporediva s efikasnostima modernih metoda.Jet reconstruction in modern physics poses problems due to detector effects and incomplete knowledge of hadronisation. The reconstruction is based on simulated events and simulated responses of the detector from which the efficiency of the reconstruction in individual channels is determined. Efficiency is then included in the measurement data of real events, which is assumed to follow the same distributions as the simulated events. In this paper, we generate a new simplified jet simulator that would be directed onto the N x N field represented by the detector. In each element of the field, for a simplified beam, an energy-momentum four-vector would be written and the whole field would represent a physical beam. Realistic image of the beam would then be obtained by introducing detector effects on the field. Finally, we’ll see if it is possible to reconstruct the physical jet from its images by using machine learning method and whether the efficiency of such reconstruction is comparable to the efficiencies of modern methods

Jet reconstruction with machine learning methods

Rekonstrukcija cijelog mlaza u modernoj fizici problematična je zbog detektorskih efekata i nepotpunog poznavanja hadronizacije. Rekonstrukcija se temelji na simulacijama događaja i simuliranom odazivu detektora iz kojeg se onda određuje efikasnost rekonstrukcije pojedinog kanala koji se razmatra. Efikasnost se tada uračunava u mjerene podatke stvarnih događaja, za koje se pretpostavlja da prate iste distribucije kao i simulirani događaji. U ovom radu bi se napravio novi, pojednostavljeni simulator mlazova koji bi usmjeravali na N x N polje koje predstavlja detektor. U svakom elementu polja, za pojednostavljeni snop, zapisao bi se četverovektor impulsa i energije te bi cjelokupno polje predstavljalo fizikalni snop. Realna slika snopa tad bi se dobila uvođenjem detektorskih efekata na polje. Konačno, vidjet ćemo je li pomoću metoda strojnog učenja moguće rekonstruirati fizikalni snop iz njegove realne slike, te je li efikasnost takve rekonstrukcije usporediva s efikasnostima modernih metoda.Jet reconstruction in modern physics poses problems due to detector effects and incomplete knowledge of hadronisation. The reconstruction is based on simulated events and simulated responses of the detector from which the efficiency of the reconstruction in individual channels is determined. Efficiency is then included in the measurement data of real events, which is assumed to follow the same distributions as the simulated events. In this paper, we generate a new simplified jet simulator that would be directed onto the N x N field represented by the detector. In each element of the field, for a simplified beam, an energy-momentum four-vector would be written and the whole field would represent a physical beam. Realistic image of the beam would then be obtained by introducing detector effects on the field. Finally, we’ll see if it is possible to reconstruct the physical jet from its images by using machine learning method and whether the efficiency of such reconstruction is comparable to the efficiencies of modern methods

Fusion hindrance and Pauli blocking in 58Ni+64Ni

The early experiments on fusion of Ni + Ni systems are well-known and indicated for the first time the possible influence of transfer reactions on sub- barrier cross sections. The influence of the positive Q-value transfer channels on sub-barrier fusion cross sections of the system 58Ni + 64Ni was evidenced in an exper- iment by Beckerman et al. Subsequent experiments for the two systems 58Ni + 58Ni and 64Ni + 64Ni showed that fusion hindrance is clearly present in both cases. The lowest measured cross section for 58Ni + 64Ni was relatively large (0.1 mb), so that no hindrance was observed. In the present measurement the excitation function has been extended by two orders of magnitude downward. The present experiment in- dicates that the flat trend of the sub-barrier cross sections for 58Ni + 64Ni continues down to the level of μb and the logarithmic slope of the excitation function increases slowly, showing a tendency to saturate at the lowest energies. No maximum of the astrophysical S-factor is observed, so fusion hindrance is not observed. This trend at far sub-barrier energies suggests that the presence of the transfer channel with Q > 0, effectively counterbalances the effect of Pauli repulsion that is predicted to reduce tunneling probability

Fusion Hindrance and Pauli Blocking in 58Ni + 64Ni

58Ni +64Ni is the first case where the influence of positive Q-value transfer channels on sub-barrier fusion was evidenced, in a very well known experiment by Beckerman et al., by comparing with the two systems 58Ni + 58Ni and 64Ni+64Ni. Subsequent measurements on 64Ni + 64Ni showed that fusion hindrance is clearly present in this case. On the other hand, no indication of hindrance can be observed for 58Ni + 64Ni down to the measured level of 0.1 mb. In the present experiment the excitation function has been extended by two orders of magnitude downward. The cross sections for 58Ni + 64Ni continue decreasing very smoothly below the barrier, down to '1 µb. The logarithmic slope of the excitation function increases slowly, showing a tendency to saturate at the lowest energies. No maximum of the astrophysical S -factor is observed. Coupled-channels (CC) calculations using a Woods-Saxon potential and includinginelastic excitations only, underestimate the sub-barrier cross sections by a large amount. Good agreement is found by adding two-neutron transfer couplings to a schematical level. This behaviour is quite different from what already observed for 64Ni+ 64Ni (no positive Q-value transfer channels available), where a clear low-energy maximum of the S -factorappears, and whose excitation function is overestimated by a standard Woods-Saxon CC calculation. No hindrance effect is observed in 58Ni+ 64Ni in the measured energy range. This trend at deep sub-barrier energies reinforces the recent suggestion that the availability of several states following transfer with Q>0, effectively counterbalances the Pauli repulsion that, in general, is predicted to reduce tunneling probability inside the Coulomb barrier

A new Time-of-flight detector for the R 3 B setup

© 2022, The Author(s).We present the design, prototype developments and test results of the new time-of-flight detector (ToFD) which is part of the R3B experimental setup at GSI and FAIR, Darmstadt, Germany. The ToFD detector is able to detect heavy-ion residues of all charges at relativistic energies with a relative energy precision σΔE/ ΔE of up to 1% and a time precision of up to 14 ps (sigma). Together with an elaborate particle-tracking system, the full identification of relativistic ions from hydrogen up to uranium in mass and nuclear charge is possible.11Nsciescopu