Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 49 (2016)

nat
Measurementof
ofproduction
production crossW(d,x)
Measurement
cross sections
sectionsof
ofRe
Reisotopes
isotopesininthe
thenatW(d,x)
reactionsreactions

Y. Komori,*1 M. Murakami,*1,*2 and H. Haba*1
Chemical characterization of superheavy elements is oneof the most important and challenging subjects in the fieldof nuclear chemistry. We plan to conduct modelexperiments for chemical studies of element 107, Bh, using
radiotracers of its homologs, Tc and Re. Long-lived 95mTc(T1/2 = 61 d), 183Re (T1/2 = 70 d), and 184m,gRe (m: T1/2 = 169d; g: T1/2 = 35.4 d) are useful for the model experiments.
These isotopes are producible in the deuteron-induced
reactions on natMo and natW (nat: natural isotopicabundance) using the RIKEN AVF cyclotron. Previously,
we measured production cross sections of Tc isotopes in thenatMo(d,x) reactions for quantitative production of 95mTc.1)
In this work, we have measured the cross sections of Reisotopes in the natW(d,x) reactions up to 24 MeV.
The cross sections were measured using a stacked-foiltechnique. The target stack consisted of twenty sets of natWfoils (99.95% purity, 40.7 mg/cm2 thickness) and natTi foils(>99.6% purity, 4.7 mg/cm2 thickness). The Ti foils wereused to calibrate the beam current and the incident energy
via the monitor reaction natTi(d,x)48V.2) The size of all foils
was 15 × 15 mm2. The target stack was irradiated for 1 hwith a 24-MeV deuteron beam supplied from the RIKEN
AVF cyclotron. The average beam current was 0.18 μA.
After the irradiation, each foil was subjected to γ-ray
spectrometry with a Ge detector.
The excitation functions were measured for thenatW(d,x)181,182a,182b,183,184m,184g,186gRe,187W,182g,184Ta reactions.
Figure 1 shows the excitation function of the natW(d,x)183Rereaction. Our results are in good agreement with those ofTárkányi et al.3) and Duchemin et al.4) and slightly smaller
than others.5–7) Figure 2 shows the excitation function of thenatW(d,x)184mRe reaction. There are only two reports4,5) onthe cross sections of 184mRe and our data confirmed theresults reported by Duchemin et al.4) It can be seen that thetheoretical model code TALYS (TENDL-2014)8) reproduces
well the experimental cross sections of 183Re. However, thecode significantly overestimates the excitation function of184m
Re though it can reproduce the shape of the function. Asfor 184gRe, our results are slightly smaller than those in theliterature.3–5) The TALYS code slightly underestimates ourexcitation function of 184gRe, though it reproduces the shapeof the function. Thick-target yields of 183,184m,184gRe werededuced from the measured cross sections. The deduced
yields of 183,184m,184gRe at 24 MeV are 1.7, 0.043, and 1.2
MBq/μA·h, respectively. Based on the present results, we
produced 183,184m,184gRe by typical irradiations of a 200
mg/cm2-thick natW target foil with the 24-MeV deuteronbeam with 5-μA for 3 h. These Re isotopes were chemicallyseparated as no-carrier-added forms from the target material
and by-products by using anion-exchange and alumina
䠆1䠆2columns. We are using these radiotracers to develop a rapid
solvent extraction apparatus and to determine suitable
experimental conditions to study the aqueous chemistry ofBh.9)
Cross section [mb]600500400300natW(d,x)183Re

This work
Duchemin (2015)
Manenti (2014)
Nakao (2006)
Tarkanyi (2003)
Ishioka (2002)
TENDL-2014

200184W(d,3n)
182W(d,n)

10000

183W(d,2n)1020
Deuteron energy [MeV]

30Fig. 1. The excitation function of the natW(d,x)183Re reaction.
The errors of the cross sections were evaluated bypropagating those of counting statistics in the radioactivity
measurement, detector efficiency, and γ-ray intensity. Theerror in the deuteron energy corresponds to the energy
degradation in each foil.
100

Cross section [mb]natW(d,x)184mRe

This work
Duchemin (2015)
Manenti (2014)
TENDL-2014

186W(d,4n)50
184W(d,2n)183W(d,n)001020Deuteron energy [MeV]

30Fig. 2. The excitation function of the natW(d,x)184mRe
reaction.
References

1) Y. Komori et al.: RIKEN Accel. Prog. Rep. 48, 296 (2015).
2) IAEA: IAEA report IAEA-TECDOC-1211, 2001.
3) F. Tárkányi et al.: Nucl. Instrum. Meth. B 211, 319 (2003).
4) C. Duchemin et al.: Appl. Radiat. Isot. 97, 52 (2015).
5) S. Manenti et al.: Radiochim. Acta. 102, 669 (2014).
6) M. Nakao et al.: Nucl. Instrum. Meth. A 562, 785 (2006).
7) N. S. Ishioka et al.: J. Nucl. Sci. Technol. Suppl. 2, 1334 (2002).
8) A. J. Koning et al.: TENDL-2014: TALYS-based EvaluatedNuclear Data Library, 2014.
9) Y. Komori et al.: Pacifichem 2015, Honolulu, Hawaii, U.S.A.,
Dec. INOR 1758, 2015.

RIKEN Nishina Center
Graduate school of Sci. and Technol., Niigata Univ.

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