Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 47 (2014)

Excitation functions for production of Nb and Ta isotopes in the(d,x) reactions on nat Zr and nat Hf up to 24 MeV
M. Murakami,∗1,∗2 H. Haba,∗1 S. Goto,∗2 and H. Kudo∗2∗1∗2

RIKEN Nishina Center
Department of Chemistry, Niigata University- 266 -sections reported by Gonchar et al.7) , those reported
by Tárkányi et al.,8) and those calculated by theTALYS code6) are compared. The data reported byGonchar et al.7) and Tárkányi et al.8) show a similar
shape of the excitation function with a systematicallyhigher magnitude. The TALYS code also indicates asimilar shape of the excitation function but lower values than the measured ones. The cross sections of thenatHf(d,x)179 Ta reaction were measured for the firsttime, as shown in Fig. 1(b). The measured excitation
function exhibits the maximum cross section of 489 ±50 mb at 21.1 ± 0.4 MeV. Again, the calculated crosssections by TALYS indicate lower values, though theshape of the excitation function is similar.
Thick-target yields of 95m,g Nb and 179 Ta were deduced from the measured cross sections and the stopping power given by the SRIM-2008 program.5) The
deduced yields for beam energies up to 24 MeV were
1.3, 0.40, and 0.21 MBq/(µA·h) for 95m Nb, 95g Nb, and179
Ta, respectively.
600

60
5040

nat

95m+gZr(d,x)
NbThis work
Gonchar (1993)
Tarkanyi (2004)
TALYS

Cross section (mb)natCross section (mb)

The isotopes 95g Nb (T1/2 = 34.991 d) and 179 Ta(T1/2 = 1.82 y) are useful radiotracers for the basicstudies of the element 105, Db. We have investigatedthe production of these radiotracers by the activationof nat Zr and nat Hf with a 14-MeV proton beam supplied by the RIKEN AVF cyclotron.1) From the AVF
cyclotron, a deuteron beam is also available.2,3) Activation by the deuteron beam is one of the widely used
and well-studied methods to produce the radiotracers.
However, the production cross sections of 95g Nb by the(d,x) reaction are scanty compared to those of the (p,x)
reactions. Furthermore, the cross sections of 179 Ta inthe (d,x) reaction have not been reported. In this work,
we measured the excitation functions for the production of 95g Nb and 179 Ta as well as other isotopes in the(d,x) reactions on nat Zr and nat Hf.
The excitation functions were measured with astacked-foil technique. For the measurement of thecross sections of Nb isotopes, thin foils of nat Zr (20µm thickness), nat Ti (20 µm thickness), and nat Ta (20µm and 10 µm thickness) were stacked alternately andused as a target. The nat Ti foils were used to determine the beam energy and intensity by measuring theexcitation function of the nat Ti(d,x)48 V reaction, andthe nat Ta foils were also used as the energy degrader.
For measurement of the cross sections of Ta isotopes,
thin foils of nat Hf (25 µm thickness) and nat Ti (20 µmthickness) were stacked alternately. The size of all thefoils was 15 × 15 mm2 . Both stacks were irradiatedby the 24-MeV deuteron beam supplied by the AVF
cyclotron for 30 min. The beam was collimated toa diameter of 9 mm, and the average beam currents
were 0.48 µA and 046 µA for the Zr/Ti/Ta and Hf/Tistacks, respectively. After irradiation and proper cooling, γ- and X-rays of each foil were measured by theGe detectors.
The production cross sections were derived by thewell-known activation formula.4) The beam energies
in the individual target foils were calculated with theSRIM-2008 program.5) The experimental data werecompared with the cross section data culculated by
the TALYS-1.4 code.6)
The cross sections of 90g,91m,92m,95m,95g,96 Nb,
95,97
Zr, and 87m,87g,88 Y were measured in thenatZr(d,x) reactions, whereas the production cross sections of 175,176,178,179,180g Ta and 175,179m2,180m,181 Hf
were measured in the nat Hf(d,x) reactions. Figure 1(a) shows the excitation function of thenatZr(d,x)95m+g Nb reaction. In Fig. 1(a), the cross30
201000510152025

Deuteron energy (MeV)

30500

179Hf(d,x) Ta
This work
TALYS

400
300
200
10000

51015202530

Deuteron energy (MeV)

Fig. 1. Excitation functions of (a) nat Zr(d,x)95m+g Nb reaction and (b) nat Hf(d,x)179 Ta reaction.

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