Measurements of the ²⁴³Am neutron capture and total cross sections with ANNRI at J-PARC

Figures & data

Table 1. Differential capture and transmission measurements of ²⁴³Am

Reference	Year	Type	Energy range
Mendoza et al. [5]	2016	Capture	0.7 eV–2.5 keV
Hori et al. [6]	2009	Capture	10 meV–400 eV
Jandel et al. [9]	2009	Capture	8 eV–250 keV
Weston et al. [10]	1985	Capture	258 eV–92.1 keV
Wisshak et al. [11]	1983	Capture	5 keV–250 keV
Belanova et al. [12]	1976	Transmission	0.35 eV–35 eV
Simpson et al. [13]	1974	Transmission	0.5 eV–1 keV
Berreth et al. [7]	1970	Transmission	8 meV–25.6 eV
Cote et al. [8]	1959	Transmission	1.4 meV–15.44 eV
This Work		Capture	10 meV–100 eV
		Transmission	4 meV–100 eV

Table 2. Thermal capture cross sections ${\sigma }_0$ provided by different integral measurements and evaluations of ²⁴³Am

Reference	Year	${\sigma }_0$(b)
This Work	2019	$87.7\pm 5.4$
Hori et al. [6]	2009	76.6
Marie et al. [14]	2006	$81.8\pm 3.6$
Hatsukawa et al. [15]	1997	84.4
Gavrilov et al. [16]	1977	$83\pm 6$
Eberle et al. [17]	1971	$77\pm 2$
Folger et al. [18]	1968	78
Bak et al. [19]	1967	$73\pm 6$
Ice et al. [20]	1966	66–84
Butler et al. [21]	1957	$73.6\pm 1.8$
Harvey et al. [22]	1954	$140\pm 50$
Stevens et al. [23]	1954	115
ENDF/B-VII.1 [24]	2011	80.4
JENDL-4.0 [25]	2011	79.3

Figure 1. Vertical cross sectional view of ANNRI.

Table 3. Characteristics of the samples

	Activities measured (MBq)
Samples	Calorimetric method	$\gamma$-ray spectrometry	Weight of Y2O3 [mg]
60-MBq ^243Am Sample	$67.3\pm 0.3$	$66.7\pm 1.3$	45
120-MBq ^243Am Sample	$155.8\pm 0.3$	$155\pm 3$	43
240-MBq ^243Am Sample	$281.8\pm 0.3$	$286\pm 6$	39
Dummy Sample	-	-	66

Table 4. Isotopic and impurity abundances of ²⁴³Am sample

	TIMS (%)	α-ray spectrometry (%)
^241Am	$2.29\pm 0.02$	$2.4\pm 0.4$
^242mAm	$0.038\pm 0.003$	Not Detected
^243Am	$97.67\pm 0.02$	$97.6\pm 4.0$
^244Cm	Not detected	$0.036\pm 0.001$

Table 5. Measuring times

Samples	Measuring time [h]
60-MBq ^243Am Sample	9
120-MBq ^243Am Sample	7.5
240-MBq ^243Am Sample	13
Dummy sample	8
Blank	8
^208Pb	12
^10B	3

Figure 2. Prompt gamma-ray pulse-height spectra of the 240-MBq ²⁴³Am sample, the dummy case, and a decay gamma-ray pulse-height spectrum from the 240-MBq ²⁴³Am sample without neutron beam measured with one of the cluster crystals. Each spectrum was normalized with the number of incident proton beam shots.

Figure 3. Gated TOF spectra per $1.79\times {10}^{10}$ protons of the ²⁴³Am samples and the dummy sample. The spectra were measured with one of the 14 crystals.

Figure 4. Typical time dependences of the dead-time correction factor for the measurements of the 240-MBq ²⁴³Am sample and the 60-MBq ²⁴³Am sample.

Figure 5. Deduced net spectra of the 240-MBq ²⁴³Am sample and that of the 60-MBq ²⁴³Am sample.

Figure 6. Correction factors for neutron self-shielding and multiple scattering on the 240-MBq ²⁴³Am sample and the 60-MBq ²⁴³Am sample.

Figure 7. Relative neutron spectrum obtained using the ¹⁰B(n,$\alpha \gamma$)⁷Li reactions and uncertainties (total, statistical uncertainty, uncertainty due to self-shielding and multiple-scattering correction).

Figure 8. Ratios of the capture yields of the 120-MBq ²⁴³Am sample and the 60-MBq ²⁴³Am sample to that of the 240-MBq ²⁴³Am sample.

Figure 9. Determined neutron capture cross sections of ²⁴³Am around the 1.356 eV resonance together with values of JENDL-4.0 for temperature of 300 K (broadened with the resolution function).

Figure 11. Normalized yield from the measurements of the ²⁴³Am samples around 1.356- and 1.744-eV resonances.

Figure 10. Derived cross section, total uncertainty, statistical uncertainty, uncertainty due to area densities, and uncertainty due to values of evaluated elastic scattering cross section.

Figure 12. The normalized yields from the measurements of the 240-MBq samples; comparison to the contribution from ²⁴³Am and Cm impurities and contribution from deduced impurities of ²⁴⁰Pu and ²³⁹Pu. The contributions were calculated using JENDL-4.0.

Figure 13. Derived cross section of the ²⁴³Am measured with the 60-MBq ²⁴³Am sample comparison to the uncertainties of the cross sections (total, statistical uncertainty, uncertainty due to normalization, uncertainty due to dead time correction, uncertainty due to self-shielding and multiple-scattering correction, uncertainty due to neutron flux, uncertainty due to the contribution of fission events, and uncertainty due to impurities).

Figure 14. Derived cross section of the ²⁴³Am measured with the 120-MBq ²⁴³Am sample comparison to the uncertainties of the cross sections (total, statistical uncertainty, uncertainty due to normalization, uncertainty due to dead time correction, uncertainty due to self-shielding and multiple-scattering correction, uncertainty due to neutron flux, uncertainty due to the contribution of fission events, and uncertainty due to impurities).

Figure 15. Derived cross section of the ²⁴³Am measured with the 240-MBq ²⁴³Am sample comparison to the uncertainties of the cross sections (total, statistical uncertainty, uncertainty due to normalization, uncertainty due to dead time correction, uncertainty due to self-shielding and multiple-scattering correction, uncertainty due to neutron flux, uncertainty due to the contribution of fission events, and uncertainty due to impurities).

Table 6. Details of uncertainties for the derived capture cross section of ²⁴³Am at neutron energy of 0.0253 eV

Samples	60-MBq sample [b]	120-MBq sample [b]	240-MBq sample [b]
Derived cross section	96	$89.5$	87.7
Statistical uncertainty^a	17	1.8	1.0
Normalization	4	4.4	4.2
Dead time correction	< 1	< 0.1	< 0.1
Self-shielding and multiple-scattering correction	< 1	< 0.1	< 0.1
Relative neutron flux	< 1	0.4	0.4
Fission events subtraction	3	3.1	3.1
Impurities	< 1	0.3	0.3
Total uncertainty	18	5.7	5.4

^aTo reduce the statistical uncertainty, the data were averaged by integrating over 10 points.

Figure 16. Obtained neutron capture cross sections of ²⁴³Am measured with the 240-MBq ²⁴³Am sample and a comparison to evaluated value in JENDL-4.0.

Figure 17. Measured pulse height spectra of the 240-MBq ²⁴³Am sample with the ⁶Li-glass and ⁷Li-glass scintillation detectors.

Figure 18. Gated TOF spectra of the 240-MBq ²⁴³Am sample and the dummy sample with the ⁶Li-glass scintillation detector and the ⁷Li-glass scintillation detector. Each TOF spectrum was normalized with the number proton beam shots.

Figure 19. Dead time of the 240-MBq ²⁴³Am sample measurements with the ⁶Li-glass detector and the ⁷Li-glass detector.

Figure 20. Transmission ratio of the 240-MBq ²⁴³Am sample.

Figure 21. Derived total cross section of ²⁴³Am, and uncertainties of the cross sections (total, statistical uncertainty, systematic uncertainty, uncertainty due to neutron intensity, and uncertainty due to impurity subtraction).

Table 7. Details of uncertainties for the derived total cross section of ²⁴³Am at neutron energy of 0.0253 eV

Derived cross section (b)	101
Statistical uncertainty (b)	7.2
Systematic uncertainty (b)	2.3
Uncertainty due to relative neutron intensity (b)	7.4
Uncertainty due to impurity subtraction (b)	1.2
Total uncertainty (b)	11

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