Introduction

Experimental activation cross section data of proton and deuteron induced reactions on platinum for production of medically relevant radioisotopes, for thin layer activation technology and for generally used activation data libraries [1,2,3,4,5,6] were reported by us earlier. The goal of this study was to clear the disagreement in our earlier measurement, and to compare all data with different theoretical models. Furthermore, we could determine new cross section for some reactions.

In our last investigation up to 50 MeV [6] we could deduce only scattered data for some activation products and for some reactions significant disagreements were found with earlier experimental data. During a recent investigation of activation data on other target elements we got the possibility to obtain additional results on platinum in the 35–49 MeV energy range. In the present report, we compare the new data with the literature values and in order to investigate the prediction capability of theoretical results we made calculations with the ALICE and EMPIRE codes, modified to better represent deuteron induced reactions.

Experimental details and data analysis

Elemental experimental cross sections were determined by using the activation method, stacked foil irradiation technique and HPGe gamma ray spectrometry. Cross-section data were deduced relative to the excitation functions of the 27Al(d,x)22,24Na monitor reactions [7] re-measured in the whole covered energy range.

The irradiation was made at an external beam line of the Cyclone 90 cyclotron of the Université Catholique in Louvain la Neuve (LLN) for 60 min with a 50 MeV energy extracted beam having 100 nA beam intensity. The targets were irradiated in a short Faraday cup.

The irradiated stack contained 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), CuMnNi alloy (24.73 μm), Al (49.54 μm), Al (49.54 μm) followed by 13 blocks of Hf (10.54 μm) Al (10.85 μm), Al (49.54 μm), CuMnNi alloy (24.73 μm) and Al (10.85 μm). The 7 Pt targets covered the 49–35 MeV energy range.

Four series of gamma-ray spectra were measured to follow the decay, starting at 7.9–8.7 h, 21.3–25.1 h, 187.2–198.2 h and 2811.1–3022.9 h after the end of bombardment, respectively. Further experimental details are given in our previous work on deuteron induced reactions on manganese [8], which was irradiated in the same stack.

Gamma spectra were evaluated by automatic fitting algorithm included in the Genie 2000 package or in an iterative process using the Forgamma [9, 10] code. For data evaluation, NUDAT 2.6 [11] decay data were used (Table 1). As natural platinum consists of several stable isotopes with following abundance (%): 190Pt–0.01, 192Pt–0.79, 194Pt–32.9, 195Pt–33.8, 196Pt–25.3, 198Pt–7.2, so called elemental cross sections were deduced.

Table 1 Decay characteristic of the investigated reaction products and Q-values of the contributing processes
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The Q values of the contributing reactions (Q value calculator [12]) are also shown in Table 1 to indicate the reaction thresholds.

Uncertainty on cross-sections was determined according to the recommendation given in Ref. [13] by taking the sum in quadrature of all individual linear contributions: beam current (7%), target thickness or homogeneity (5%), detector efficiency (5%), photo peak area determination and counting statistics (1–20%).

The median beam energy in each target foil was obtained by a degradation calculation based on the calibrated primary energy, the stopping powers of Andersen [14] and the fitted monitor reactions (Fig. 1) [15]. Uncertainty of energy was estimated by taking into account cumulative effects during the energy degradation (primary energy, target thickness, energy straggling) and the applied correction to monitor reactions.

Fig. 1
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Simultaneously measured experimental data of 27Al(d,x)22,24Na monitor reactions in comparison with the recommended values [7]

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Abundance of isotopes of natural Pt (%): 190Pt–0.01, 192Pt–0.79, 194Pt–32.9, 195Pt–33.8, 196Pt–25.3, 198Pt–7.2.

The Q-values shown in Table 2 refer to formation of the ground state. Decrease Q-values for isomeric states with level energy of the isomer.

Table 2 The measured cross sections for the natPt(d,xn)191,192,193,194,195,196m2,196g,198m,198g,199Au, natPt(d,x)189,191,193m,195m,197gPt and natPt(d,x)189,190m,190,192,194m2Ir reactions
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When complex particles are emitted instead of individual protons and neutrons the Q-values have to be decreased by the respective binding energies of the compound particles: pn → d + 2.2 MeV, p2n → t + 8.5 MeV, 2pn → 3He + 7.7 MeV, 2p2n → α + 28.3 MeV.

Theoretical calculations

The cross sections of the investigated reactions were calculated using the pre-compound model codes ALICE-IPPE [16] and EMPIRE-II [17] modified for deuterons by Ignatyuk (D-versions) [18]. These modified codes named ALICE-D and EMPIRE-D were developed by including a simulation of direct (d, p) and (d, t) transitions with the general relations for a nucleon transfer probability in the continuum through an energy dependent enhancement factor for the corresponding transitions. The theoretical curves were determined using one recommended input data-set [19] without any optimization or adjustment of parameters to the individual reactions or stable target isotopes. Independent data for isomers with ALICE-D code were obtained by using the isomeric ratios calculated with EMPIRE-D.

The experimental data are also compared with the cross section data reported in the TENDL-2017 [20] on-line nuclear reaction data library. The TENDL-2017 library is based on both default and adjusted TALYS 1.9 model calculations [21].

We had many problems with these calculations. At the beginning the optical potential for deuterons was taken in accordance with the default RIPL recommendations [22]. As for this potential all Empire results were much higher than he ALICE results, we decided to make new calculations with the Perry potential [23], which we used earlier for the 197Au target [24]. This resulted in certainly more consistency. However, the main problems relate to the levels schemes, which are poor for the most of Pt and Ir isotopes. There are too many low-value spin- and a strong deficit for high-spin levels. So, the calculated isomeric ratios are too low for most cases. In principle some corrections for the spin distributions can be made to get better agreement.

Results and discussion

The measured experimental cross-section data are shown in Figs. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22 and 23. The numerical values are presented in Table 2. The investigated radio-products can be produced directly, through the internal transition of a long-lived isomeric state and through the decay of an isobaric parent. We made theoretical model calculations also for production of a few radioisotopes measured by us earlier, but no new experimental data are presented in this study. Agreement of the available experimental data and the theoretical data can clearly be seen in the figures of the present work. The comparisons result in different conclusions for each reaction, which is hard to explain. Some more detailed discussions are available in our previous work [6]. Therefore, in the summary we present only general conclusion on the predictive capability of the model calculations.

Fig. 2
figure 2

Excitation function of the natPt(d,x)199Au(cum) reaction in comparison with literature and theoretical values

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Fig. 3
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Excitation function of the natPt(d,x)198mAu reaction in comparison with literature and theoretical values

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Fig. 4
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Excitation function of the natPt(d,xn)198gAu reaction in comparison with literature and theoretical values

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Fig. 5
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Excitation function of the natPt(d,xn)196m2Au reaction in comparison with literature and theoretical values

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Fig. 6
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Excitation function of the natPt(d,xn)196gAu (cum) reaction in comparison with literature and theoretical values

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Fig. 7
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Excitation function of the natPt(d,xn)195Au (cum) reaction in comparison with literature and theoretical values

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Fig. 8
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Excitation function of the natPt(d,xn)194Au reaction in comparison with literature and theoretical values

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Fig. 9
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Excitation function of the natPt(d,xn)193Au(cum) reaction in comparison with literature and theoretical values

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Fig. 10
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Excitation function of the natPt(d,xn)192Au reaction

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Fig. 11
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Excitation function of the natPt(d,xn)191Au reaction in comparison with literature and theoretical values

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Fig. 12
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Excitation function of the natPt(d,xn)197mPt reaction in comparison with theoretical values

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Fig. 13
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Excitation function of the natPt(d,x)197gPt(m+) (cum) reaction in comparison with literature and theoretical values

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Fig. 14
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Excitation function of the natPt(d,xn)195mPt reaction in comparison with literature and theoretical values

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Fig. 15
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Excitation function of the natPt(d,xn)193mPt reaction in comparison with theoretical values

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Fig. 16
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Excitation function of the natPt(d,xn)191Pt reaction in comparison with literature and theoretical values

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Fig. 17
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Excitation function of the natPt(d,xn)189Pt reaction in comparison with literature and theoretical values

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Fig. 18
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Excitation function of the natPt(d,xn)188Pt reaction in comparison with theoretical values

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Fig. 19
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Excitation function of the natPt(d,xn)194m2Ir reaction in comparison with literature and theoretical values

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Fig. 20
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Excitation function of the natPt(d,xn)192Ir reaction in comparison with literature and theoretical values

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Fig. 21
figure 21

Excitation function of the natPt(d,xn)190m2Ir reaction in comparison with theoretical values

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Fig. 22
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Excitation function of the natPt(d,xn)190Ir reaction in comparison with literature and theoretical values

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Fig. 23
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Excitation function of the natPt(d,xn)189Ir reaction in comparison with literature and theoretical values

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Radioisotopes of gold

nat Pt(d,x) 199 Au(cum) reaction

The measured cross-sections of the 199Au (T1/2 = 3.139 d) are cumulative, produced directly through the 198Pt(d,n) reaction and contribution of the β−-decay of the shorter-lived parent 199Pt (T1/2 = 30.8 min) produced through the 198Pt(d,p) process (Fig. 2). A good agreement with the earlier experimental studies [6, 7] in the overlapping energy interval is seen. Because none of the theoretical model code gave acceptable predictions for the experimental values an estimated prediction from the systematics has also be presented in Fig. 2, which is proved to be the best approximation both in trend and in values.

nat Pt(d,x) 198m Au reaction

We could obtain cross section data for both longer-lived states of 198Au. The cross sections for the 198mAu (T1/2 = 2.272 d, IT 100%) isomeric state are shown in Fig. 3. An acceptable continuation to higher energy of the data of Ditroi et al. [4] is seen. All the three model codes predict a large peak around 16–17 MeV, which was not confirmed by any of the experiments.

nat Pt(d,xn) 198g Au reaction

Independent, low, cross sections for direct production of the ground state of 198Au (T1/2 = 2.6947 d) are shown in Fig. 4 and are in acceptable agreement with the earlier values. The trends given by all model codes are good. The best value is estimated by the EMPIRE-D above 20 MeV, but it overestiimates strongly around the maximum.

nat Pt(d,xn) 196m2 Au reaction

Direct production cross-sections for the T1/2 = 9.6 h isomeric state 196m2Au are shown in Fig. 5 and agree well with the Ditroi et al. [6] data. All theoretical model codes recognize the two maxima, but all overestimate the experimental values.

nat Pt(d,xn) 196g Au(cum) reaction

The cross sections for cumulative formation of the ground state 196gAu (T1/2 = 6.1669 d) measured after the complete decay of the two higher laying, short-lived, isomeric states (m2–T1/2 = 9.6 h, m1–T1/2 = 8.1 s) are shown in Fig. 6. Very good agreement with Ditroi et al. [6] was observed. All model codes describe the shape of the excitation function almost correctly, the best value approximation is given by the EMPIRE-D code.

nat Pt(d,xn) 195 Au(cum) reaction

The cross-sections for formation of 195Au (T1/2 = 186.01 d) contain the decay of the T1/2 = 30.5 s isomeric state (Fig. 7) and are lower than the rather scattered data of Ditroi et al. [6]. The theoretical codes follow the trend of the experimental curves, but give different value predictions.

nat Pt(d,xn) 194 Au reaction

The excitation functions for production of the directly produced 194Au (T1/2 = 38.02 h) are shown in Fig. 8 and are in perfect agreement with Ditroi et al. [6]. The theoretical model codes give different values around the maxima, their approximation is acceptable only below 20 MeV.

nat Pt(d,xn) 193g Au(cum) reaction

The measured cross-sections of 193gAu (T1/2 = 17.65 h) include the internal decay of the T1/2 = 3.9 s isomeric state (Fig. 9) additional to the direct production. The new measurements are about 20% higher than a part of the values in Ditroi et al. [6] but seem to agree better with the 2006 values [4]. All the theoretical model codes strongly overestimate the experimental values.

nat Pt(d,xn) 192 Au reaction

The activation cross sections for production of 192Au (T1/2 = 4.94 h) are shown in Fig. 10 and are between our earlier values given in Refs. [4] and [6]. The best prediction is given by the TENDL-2017, both other model codes strongly overestimate the experimental values.

nat Pt(d,xn) 191 Au reaction

The cross section data of 191Au (T1/2 = 3.18 h) include the contribution from the decay of the simultaneously produced short half-life isomeric state (T1/2 = 0.92 s, 100% IT) (Fig. 11). Good overall agreement with Ditroi et al. [6]. Only TENDL-2017 follows correctly the trend of the experimental values with considerable overestimation.

Radioisotopes of platinum

nat Pt(d,x) 197m Pt reaction

We could not deduce cross section data for production of the 197mPt (T1/2 = 95.41 min), due to the long cooling time before measuring the first spectra. The earlier experimental data and the theoretical predictions are shown in Fig. 12. In spite of the large experimental uncertainties the best approximation is given by the TENDL-2017.

nat Pt(d,x) 197g Pt(m +) (cum) reaction

The measured production cross-section of 197gPt (T1/2 = 19.8915 h) is including the direct production, the contribution from internal transition (T1/2 = 95.41 min, IT: 96.7) of the isomeric state and from the β− decay of the short-lived 197m,gIr isomers (T1/2 = 5.8 min and 8.9 min, respectively) (Fig. 13). Our new measurements are in better agreement with the Ditroi et al. [4] values than with the results in Ditroi et al. [6]. All the three theoretical model codes show the trend of the experimental values, but strongly underestimate them. Only the prediction of EMPIRE-D is closed to the experimental results above 25 MeV. Even the systematics cannot reconstruct the experimental results.

nat Pt(d,x) 195m Pt reaction

The excitation function of the high spin isomeric state (T1/2 = 4.02 d) of 195Pt is shown in Fig. 14 and confirm overall the previously measured values of [4] and [6]. All theoretical predictions follow the trend of the experimental values, but TENDL strongly overestimates, while ALICE-D and EMPIRE-D giving approximately the same underestimated values.

nat Pt(d,x) 193m Pt reaction

The cross sections for production of 193mPt (T1/2 = 4.33 d, IT: 100%) are shown in Fig. 15. They include the contribution of 0.03% EC decay of 193mAu (T1/2 = 3,9 s). No earlier experimental data were found. Only the TENDL-2017 prediction gives an acceptable trend but with slight overestimation.

nat Pt(d,x) 191 Pt(cum) reaction

The cumulative cross-sections for production of 191Pt (T1/2 = 2.802 d) includes direct production and formation through decay of 191Au (T1/2 = 3.18 h) and is shown in Fig. 16. Above 40 MeV the new values are significantly lower than the Ditroi et al. [6] data. The three theoretical model calculations give different results, the best approximation is given by the EMPIRE-D up to 40 MeV, but above this energy the TENDL-2017 predictions are better.

nat Pt(d,x) 189 Pt(cum) reaction

The cross-sections for production of 189Pt (T1/2 = 11 h) are cumulative, measured after the complete decay of the two longer-lived states of the parent 189Au (T1/2 = 4.6 min and 28.3 min) radioisotope (Fig. 17). Good agreement of the few data points with the earlier measurement [6] was found. In this energy range all the three theoretical codes give acceptable predictions.

nat Pt(d,x) 188 Pt(cum) reaction

Only a single cross section point for formation of 188Pt (T1/2 = 10.2 d) is available, reported in earlier work [6] (Fig. 18). The cross-section contains the contribution of the direct production and the simultaneous decay of the 188Au (T1/2 = 8.8 min) parent. The theoretical model codes give very different predictions.

Radioisotopes of iridium

nat Pt(d,x) 194m2 Ir reaction

The measured spectra allow to get cross sections only for the second, long-lived (T1/2 = 171 d) metastable state (Fig. 19) out of the three longer-lived states of 194Ir. Overall agreement between the new values and Ditroi et al. [6] was seen. TENDL-2017 and ALICE-D give similar trends, but with over- and underestimation. The EMPIRE-D prediction is much lower.

nat Pt(d,x) 192 Ir(cum) reaction

Our experimental data (Fig. 20) include the direct production of the ground state (T1/2 = 3.8 d) and the decay of the short-lived isomeric state192m1Ir (T1/2 = 1.45 min). Overall agreement between the new values and Ditroi et al. [6] was seen. ALICE-D gives good approximation of the measured values in the whole energy region, while EMPIRE-D slightly overestimates. TENDL-2017 gives strong underestimated prediction.

nat Pt(d,x) 190m2 Ir reaction

The production cross sections of the second, high spin isomeric state 190m2Ir (T1/2 = 3.25 h) are shown in Fig. 21 and agree well with the TENDL-2017 prediction while the values of the other codes are 4–10 times too high. No earlier experimental data are available in the literature.

nat Pt(d,x) 190 Ir(m +) reaction

The measured cross sections of the ground state (T1/2 = 11.8 d) include, in addition to the direct production, the decay of the first metastable state 190m1Ir (T1/2 = 1.2 h, IT 100%) and the second high-spin isomeric state 190m2Ir (T1/2 = 3.25 h, IT 5.6%) (Fig. 22). Our new values are about 10% lower than Ditroi et al. [6]. TENDL-2017 underestimates, while EMPIRE-D and ALICE-D overestimate the experimental values.

nat Pt(d,x) 189 Ir(cum) reaction

The cross-section determined for 189Ir (T1/2 = 13.2 d) is cumulative and contains the direct production and the contribution from the decay of 189Pt (T1/2 = 10.87 h) (Fig. 23). Perfect agreement with Ditroi et al. [6] was found. In this energy region the TENDL-2017 prediction is acceptable, while the ALICE-D and EMPIRE-D results overestimate the experimental values.

nat Pt(d,x) 188 Ir(cum) reaction

The cross-section determined for 188Ir (T1/2 = 41.5 h) is cumulative and contains the direct production and the contribution from the decay of 188Pt (T1/2 = 10.2 d) (Fig. 24). In this energy region the TENDL-2017 prediction is acceptable with slight overestimation, while the ALICE-D and EMPIRE-D results overestimate the experimental values.

Fig. 24
figure 24

Excitation function of the natPt(d,xn)188Ir reaction in comparison with literature and theoretical values

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Summary and conclusion

We report on new experimental cross sections leading to formation of natPt(d,xn)191,192,193,194,195,196m2,196g,198m,198g,199Au, natPt(d,x)189,191,193m,195m,197gPt and natPt(d,x)188,189,190m2,190,192,194m2Ir in the 35–49 MeV energy range. For production of 193mPt and 188,190mIr no earlier experimental data were found. A partial or good agreement was found with the results of our previous studies in the overlapping energy regions, but some cases there are large disagreements. The comparison with the theoretical predictions of TENDL-2017 shows moderate agreement or large disagreement especially for isomeric cross sections. The situation is nearly same in the case of ALICE-D and EMPIRE-D, which underline the importance of experimental data that can help to still improve the codes and models, especially for deuteron induced reactions.

The EMPIRE and TALYS are more recent and advanced codes comparing to ALICE. In practical applications the TALYS based TENDL library is most widely used due to availability of the calculated data in the web. In case of all codes there are significant problems for deuteron induced reactions. Therefore, detailed improvement in the model codes are under development in a few laboratories. The ALICE-D and Empire-D are one way of improvement by using correction, based on systematics.

Knowing the results and adjusting the used parameters a better agreement can be reached. The aim of our calculation and comparison was to show the predictivity by standard parameters, illustrating reliability of the model codes in case of unmeasured excitation functions.