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Study of Nucleon Charge-Exchange Processes at $^{12}$C Fragmentation with an Energy of 300 MeV/Nucleon

A. A. Kulikovskaya, M. A. Martemianov

TL;DR

The study reports the first measurements of nucleon charge-exchange in the 300 MeV/nucleon energy region using the FRAGM fragment separator at TWAC, focusing on fragmentation of 12C on Be and detecting 11Be, 12B, and 12Be as products. Differential cross sections are extracted as functions of fragment momentum and compared to BC, INCL, and QMD nucleus-nucleus interaction models, revealing that BC best reproduces momentum shapes while INCL misses the single-quasielastic peak and QMD matches shapes but differs in absolute yields. The analysis includes identification of fragments via TOF and energy-loss correlations, simulation of the magneto-optical channel with Geant4, and corrections for detection efficiency and momentum resolution, achieving a momentum accuracy of about 0.4%. The results show that charge-exchange cross sections are two orders of magnitude smaller than non-charge-exchange fragmentation and provide upper limits for 12N production, highlighting the role of neutron-proton asymmetry in the Be target and the importance of resonance and meson-exchange dynamics in light-nucleus fragmentation. Overall, the work extends empirical data on light-nucleus charge-exchange, tests and informs theoretical models, and supplies benchmarks relevant to nuclear structure studies and applications in medical physics and radiation protection.

Abstract

The search of reactions with nucleon charge-exchange was performed on the FRAGM fragment-separator of the TWAC accelerator complex at fragmentation of carbon nuclei with an energy of 300 MeV/nucleon on a thin beryllium target. The experimental setup, located at an angle of 3.5 degrees to the incident beam, had high momentum resolution. Differential cross sections were measured for $^{11}$Be, $^{12}$B and $^{12}$Be as function of the nuclei momentum. The experimental data were compared with theoretical predictions of various models of nucleus-nucleus interactions and other experimental results. Measurements of nucleon charge exchange processes in this energy region was carried out for the first time. New results were obtained to test theoretical models of nucleus-nucleus interactions.

Study of Nucleon Charge-Exchange Processes at $^{12}$C Fragmentation with an Energy of 300 MeV/Nucleon

TL;DR

The study reports the first measurements of nucleon charge-exchange in the 300 MeV/nucleon energy region using the FRAGM fragment separator at TWAC, focusing on fragmentation of 12C on Be and detecting 11Be, 12B, and 12Be as products. Differential cross sections are extracted as functions of fragment momentum and compared to BC, INCL, and QMD nucleus-nucleus interaction models, revealing that BC best reproduces momentum shapes while INCL misses the single-quasielastic peak and QMD matches shapes but differs in absolute yields. The analysis includes identification of fragments via TOF and energy-loss correlations, simulation of the magneto-optical channel with Geant4, and corrections for detection efficiency and momentum resolution, achieving a momentum accuracy of about 0.4%. The results show that charge-exchange cross sections are two orders of magnitude smaller than non-charge-exchange fragmentation and provide upper limits for 12N production, highlighting the role of neutron-proton asymmetry in the Be target and the importance of resonance and meson-exchange dynamics in light-nucleus fragmentation. Overall, the work extends empirical data on light-nucleus charge-exchange, tests and informs theoretical models, and supplies benchmarks relevant to nuclear structure studies and applications in medical physics and radiation protection.

Abstract

The search of reactions with nucleon charge-exchange was performed on the FRAGM fragment-separator of the TWAC accelerator complex at fragmentation of carbon nuclei with an energy of 300 MeV/nucleon on a thin beryllium target. The experimental setup, located at an angle of 3.5 degrees to the incident beam, had high momentum resolution. Differential cross sections were measured for Be, B and Be as function of the nuclei momentum. The experimental data were compared with theoretical predictions of various models of nucleus-nucleus interactions and other experimental results. Measurements of nucleon charge exchange processes in this energy region was carried out for the first time. New results were obtained to test theoretical models of nucleus-nucleus interactions.
Paper Structure (14 sections, 3 equations, 14 figures, 1 table)

This paper contains 14 sections, 3 equations, 14 figures, 1 table.

Table of Contents

  1. INTRODUCTION
  2. REVIEW OF REACTIONS WITH NUCLEON CHARGE-EXCHANGE
  3. EXPERIMENT FRAGM AT THE ACCELERATOR-STORAGE COMPLEX TWAC
  4. Accelerator complex ТWAC.
  5. Experimental setup FRAGM.
  6. Simulation of ion beam passage in a magneto-optical channel.
  7. DIFFERENTIAL CROSS SECTIONS OF REACTIONS WITH NUCLEON CHARGE-EXCHANGE
  8. Model description of nucleus-nucleus interactions.
  9. Identification of fragments on the FRAGM magnetic spectrometer.
  10. Differential cross sections of $^{11}$B and $^{12}$B produced in a single nucleon charge-exchange.
  11. Calculation of the upper limit of $^{12}$N production.
  12. Search for fragments obtained as a result of double nucleon charge-exchange.
  13. Statistical models of fragmentation processes.
  14. CONCLUSION

Figures (14)

  • Figure 1: Schematic view of the processes of quasi-elastic interaction of nucleons of the projectile nucleus ($N_p$) and the target ($N_t$) ( a and b) and the inelastic channel accompanied by the $\Delta$-isobar production ( c and d) PaperIntr6.
  • Figure 2: Layout of the FRAGM experimental setup PaperIntr10.
  • Figure 3: Correlation distribution of the time-of-flight (TDC channels) and signal amplitude (QDC channels) for two rigidities of the magneto-optical channel of the FRAGM experiment.
  • Figure 4: Proton and ion detection efficiency by the magneto-optical channel of the FRAGM setup depending on the channel rigidity PaperIntr10.
  • Figure 5: Momentum as a function of angle for $^{12}$B produced in a charge-exchange reaction for three models of nucleus-nucleus interactions: BC ( a), INCL ( b) and QMD ( c).
  • ...and 9 more figures