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Excitation function measurement of $^{144}$Sm($α$,n) reaction at sub-Coulomb energies and detailed covariance analysis

Tanmoy Bar, Dipali Basak, Lalit Kumar Sahoo, Sukhendu Saha, Jagannath Datta, Sandipan Dasgupta, Chinmay Basu

Abstract

The cross-section measurement of $^{144}$Sm($α$,n)$^{147}$Gd (T$_{1/2}=$38.06(12) h) reaction has been performed at sub-Coulomb energies around 14$-$21 MeV ($V_{coul}\approx 21.8$ MeV) using the stacked foil activation technique. Irradiated targets were prepared from enriched (67\%) $^{144}$Sm$_2$O$_3$ powder using molecular deposition technique between thickness 280$-$350 $μ$g/cm$^2$ on high purity Al backing. A detailed simulation has been carried out to address the energy uncertainty in the irradiated beam energy followed by a comprehensive discussion of various uncertainties in the form of covariance and correlation matrices. Finally the excitation functions are compared with the previously measured experimental data from literature and the theoretical predictions obtained using Hauser-Feshbach statistical model code.

Excitation function measurement of $^{144}$Sm($α$,n) reaction at sub-Coulomb energies and detailed covariance analysis

Abstract

The cross-section measurement of Sm(,n)Gd (T38.06(12) h) reaction has been performed at sub-Coulomb energies around 1421 MeV ( MeV) using the stacked foil activation technique. Irradiated targets were prepared from enriched (67\%) SmO powder using molecular deposition technique between thickness 280350 g/cm on high purity Al backing. A detailed simulation has been carried out to address the energy uncertainty in the irradiated beam energy followed by a comprehensive discussion of various uncertainties in the form of covariance and correlation matrices. Finally the excitation functions are compared with the previously measured experimental data from literature and the theoretical predictions obtained using Hauser-Feshbach statistical model code.
Paper Structure (14 sections, 6 equations, 9 figures, 7 tables)

This paper contains 14 sections, 6 equations, 9 figures, 7 tables.

Table of Contents

  1. Introduction
  2. Experiment
  3. Target preparation
  4. Preparation of the target stacks and irradiation setup
  5. Irradiation energy determination using GEANT4
  6. Measurement of $\gamma-$ray activity
  7. Detector efficiency calibration
  8. Efficiency correction due to summing and sample geometry
  9. Detector efficiency curve
  10. Data Analysis
  11. Calculation of reaction cross section
  12. Statistical model estimation
  13. Covariance analysis
  14. Discussion and Conclusion

Figures (9)

  • Figure 1: Target stack setup and target positions for multiple target irradiation.
  • Figure 2: Targets irradiation setup with electron suppressor and water cooled flange.
  • Figure 3: Effective irradiation energy and energy straggling for the Stack 1 targets obtained from GEANT4 simulations.
  • Figure 4: Same as Figure \ref{['geant4-1']} but for Stack 2 targets.
  • Figure 5: Schematic diagram of detection setup used for $\gamma-$ spectroscopy measurement.
  • ...and 4 more figures