Introduction

Activation cross sections of residual nuclides with deuteron are basic data for applications around modern accelerators e.g. in radiation dose estimations for accelerator and target technology, in medical isotope production, in radio-analytical studies for biomedical research and wear control by thin layer activation technique. The status of experimental database for deuteron induced reactions—opposite to protons- is very poor (especially above 15 MeV), no systematical study has been performed earlier and in the published data (except for a few well measured monitor and medically important reactions) show large discrepancies. We hence performed a systematic experimental study of deuteron induced activation cross sections for around 60 elements during the last decades. A systematic comparison with the theoretical models allows conclusions on the predictivity of the different nuclear reaction model codes (ALICE-IPPE, EMPIRE-II, GNASH, TALYS, PHITS).

Manganese metal is an important component of different alloys used in nuclear technology. The experimental activation cross sections data are important for further development of the theoretical codes for deuteron induced nuclear reactions and for optimization of production routes of some medically relevant radionuclides 52gMn [1] and 51Cr [2].

In spite of the scientific and practical interest, only a couple of authors published cross section data on deuteron induced reactions on Mn. Gilly et al. [3], Baron et al. [4] and Coetzee et al. [5] studied the excitation functions of (d, p) reactions up to 12 MeV. Ochiai et al. [6] measured the cross section of the activation product 54Mn at 39.5 MeV and our group investigated the excitation functions for the production of 56,54,52Mn and 51Cr (Ditroi et al. [7]).

Thick target yields data were reported by Bondarenko and Rudenko [8] using 3 MeV deuterons for activation analysis; Vakilova et al. [9] also investigated the production yield for the determination of trace elements by deuteron activation. Dmitriev et al. [10] made a systematic study of thick target yields at 22 MeV deuterons induced reactions on a large number of target elements.

In the present work we determined the production cross-section of 56,54,52Mn, 48V and 51Cr in the 50 MeV deuteron induced activation of 55Mn. This has been done to extend the 55Mn(d, x) reaction cross-sections up to the deuteron energy of 50 MeV.

Experiment and data evaluation

For the cross section determination an activation method, based on stacked foil irradiation followed by γ-ray spectrometry was used. The stack consisted of a sequence of 7 blocks of Hf (10.54 μm), Al (49.54 μm), Al (49.54 μm), Pt (19.29 μm), Al (49.54 μm), Al (49.54 μm), NiMnCu alloy (24.73 μm), Al (49.54 μm), Al (49.54 μm) foils, repeated seven times and bombarded for 3600 s with a 50 MeV proton beam of 100 nA at Louvain la Neuve cyclotron laboratory. The activity produced in the targets and monitor foils was measured non-destructively (without chemical separation) using a high resolution HPGe gamma-ray spectrometer. The evaluation of the gamma-ray spectra was made by both a commercial and an interactive peak fitting codes.

The decay data were taken from the online database NuDat2 [11] and the Q-values of the contributing reactions from the Q-value calculator [12].

The effective beam energy and the energy scale were determined initially by a stopping calculation and finally corrected on the basis of the excitation functions of the 24Al(p, x)22,24Na monitor reactions simultaneously re-measured over the whole energy range. For estimation of the uncertainty of the median energy in the target samples and in the monitor foils, the cumulative errors influencing the calculated energy (incident proton energy, thickness of the foils, beam straggling) have been taken into account. The beam intensity was obtained on the basis of the excitation functions of the monitor reactions. The uncertainty on each cross-section was estimated by taking the square root of the sum in quadrature of all individual contributions.

The important experimental parameters and the methods of data evaluation for this work are summarized in Table 1. The targets consisted of a Ni–Mn–Cu alloy with known composition (Ni: 2%—Mn: 12%—Cu: 86%) and in principle the investigated products (56,54,52Mn, 48V and 51Cr) could, apart from reactions on 55Mn, also be produced by nuclear reactions on the other two alloy components. The cross sections for activation of these product nuclides on Ni and Cu by deuterons were, however, investigated by us earlier [13, 14]. Based on the published results and on the target composition we only had to introduce negligible corrections to the cross sections derived in the present study. The decay data used are presented in Table 2.

Table 1 Important parameters of the experiments and methods of data evaluations
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Table 2 Decay characteristics of the activation products
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Theoretical calculations od cross sections

The results for model calculations, performed up to 50 MeV, are taken from our previous study [7]. The updated ALICE-IPPE-D [24] and EMPIRE-D [25] codes were used to compare with the experimental results. As described in detail in Tarkanyi et al. [27] and Hermanne et al. [28] these improved codes were developed to achieve a better description of deuteron induced reactions. In the original versions of the programs a simulation of direct (d, p) and (d, t) phenomena is applied through an energy dependent enhancement factor for the transitions in question. The selection of parameters is given in [29]. The theoretical data from the recently updated TENDL-2017 [30] library (based on the modified TALYS 1.9 code [31]) was also used for a comparison.

Cross sections

The cross sections for reactions studied are shown in Figs. 1, 2, 3, 4 and 5 and the numerical values are collected in Table 3.

Fig. 1
figure 1

Experimental and theoretical excitation functions for the 55Mn(d, p)56Mn reaction

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Fig. 2
figure 2

Experimental and theoretical excitation functions for the 55Mn(d, x)54Mn reaction

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Fig. 3
figure 3

Experimental and theoretical excitation functions for the 55Mn(d, x)52gMn cumulative reaction

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Fig. 4
figure 4

Experimental and theoretical excitation functions for the 55Mn(d, x)51Cr reaction

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Fig. 5
figure 5

Experimental and theoretical excitation functions for the 55Mn(d, x)48V reaction

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Table 3 Production cross sections of deuteron induced reactions on manganese
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55Mn(d, p)56Mn reaction

The excitation function for 56Mn (T1/2 = 2.5789 h) radioisotope, formed by the 55Mn(d, p)56Mn reaction, is shown in Fig. 1, together with the previous experimental data and theoretical calculations. The agreement of our new data with the literature values in the studied energy range is acceptable. When comparing all experimental data with the results of theoretical calculations the agreement is good in case of ALICE-IPPE-D and EMPIRE-D up to 15 MeV but above this energy the theoretical values decrease faster. A significant difference in the magnitude of the cross sections is observed for TENDL-2017.

55Mn(d, x)54Mn reaction

For production of 54Mn (T1/2 = 312.20 days) the previously published single data point of Ochiai et al. [6] and our earlier data [7] are in good agreement with the new results (Fig. 2). The theoretical descriptions are acceptable regarding the shape, but the overestimation is significant especially around the maximum. The best agreement can be observed with the EMPIRE-D up to 25 MeV and above 40 MeV. The maximum energy of the excitation function curve is estimated almost correctly by the EMPIRE-D.

55Mn(d, x)52Mn reaction

The long-lived radionuclide 52Mn (T1/2 = 5.591 days for the ground state) is produced via the reaction 55Mn(d, p4n) with high threshold and through the decay of shorter-lived parent 52Fe (T1/2 = 8.725 h, Q = 37.9 MeV). We could not identify the gamma-lines of 52Fe in our spectra (Eγ = 168.688 keV, Iγ = 99.2%), but the presented cross section values are cumulative and include also the small contribution by isomeric decay (1.75%) of the short-lived metastable state 52mMn. The data of the different theoretical codes show large differences (Fig. 3), ALICE and above 45 MeV and EMPIRE underestimates in the same energy range.

55Mn(d, x)51Cr reaction

The practical threshold around 20 MeV indicates that the main contributing process for production of 51Cr (27.701 days) is the 55Mn(d, α2n) reaction and that contributions of the high threshold, short half-life, 51Fe–51Mn decay chain is negligible. The new data are in good agreement with our previous lower energy data (Fig. 4). There are large disagreements between the different theoretical predictions and consequently with the experimental data. Only ALICE-D produces partial agreement up to 35 MeV.

55Mn(d, x)48V reaction

We obtained only a few cross section data points for production of 48V (T1/2 = 15.9735 days) through clustered emission near the reaction threshold (Fig. 5). The data points could only be measured with relatively large errors. Comparable theoretical predictions could only be found in the TENDL-2017 on-line library and this calculation strongly underestimates the experimental data.

Thick target yields

Thick target yields (integral yields for a given bombarding energy down to the threshold of the reaction) were calculated for 56,54,52Mn and 51Cr from fitted curves to our experimental cross section data The results for physical yields [22, 23] are presented in Fig. 6.

Fig. 6
figure 6

Integral yields for production of 56,54,52Mn and 51Cr deduced from the excitation functions

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Summary

Excitation functions for the production of 56,54,52Mn, 51Cr and 48V by deuteron irradiation of monoisotopic manganese targets were determined. Out of the investigated reactions no earlier data were available for 48V while for 54,52Mn and 51Cr practically only our recently measured and published experimental data exists showing good agreement in the overlapping energy range. For the production of 56Mn, more earlier experimental data are available, which show only moderate agreement with our new results. Comparison of our experimental results with the predictions of theoretical codes show rather variable agreement. The disagreement is very significant in some cases.

Concerning the possible applications, manganese is a significant alloying element for different iron containing end even iron-free alloys. Knowledge of the deuteron-induced activation cross sections up to higher energies is important for improvement of recommended data for different activation data libraries: for Fusion Evaluated Nuclear Library [32], for JANIS Book of deuteron-induced cross-sections [33, 34] and for European Activation File [35] for calculation of induced activity for the high intensity deuteron accelerators (IFMIF [34, 36] Spiral [37] and other accelerator driven neutron sources [38]).