[en] The CNO cycle is one of the fundamental processes of hydrogen burning in stars. The first reaction of the cycle is the radiative proton capture on ${}^{12}$C and the rate of this ${}^{12}$C(p,γ)${}^{13}$N reaction is related to the ${}^{12}$C/${}^{13}$C ratio observed e.g. in the Solar System. The low-energy cross section of this reaction was measured several times in the past, however, the experimental data are scarce in a wide energy range especially around the resonance at 1.7 MeV. In the present work the ${}^{12}$C(p,γ)${}^{13}$N cross section was measured between 300 and 1900 keV using the activation method. This method was only used several decades ago in the low-energy region. As the activation method provides the total cross section and has uncertainties different from those of the in-beam γ-spectroscopy technique, the present results provide a largely independent data set for future low-energy extrapolations and thus for astrophysical reaction rate calculations.

[en] The activation method is a widely used technique to measure charged-particle induced cross sections for astrophys-ical applications. This two step technique is used for example to measure alpha-induced cross sections in γ-process related studies. The first step – in which a target is irradiated with a proton/alpha beam – is followed by the determination of the produced activity. Especially in p-process related studies in the heavier mass range, the produced radioactive nuclei decays mainly with electron-capture, resulting intense x-rays. The activity of the reaction products hence can be determine via the counting of these x-rays, and not only by counting the usually much weaker γ-rays. In this paper we compare the minimum detectable activity (MDA) of two High Purity Germanium (HPGe) detectors used for x- and γ-ray counting in activation experiments

[en] For the better understanding of the astrophysical γ-process the experimental determination of low energy proton- and α-capture cross sections on heavy isotopes is required. The existing data for the ⁹²Mo(p,γ)⁹³Tc reaction are contradictory and strong fluctuation of the cross section is observed which cannot be explained by the statistical model. In this paper a new determination of the ⁹²Mo(p,γ)⁹³Tc and ⁹⁸Mo(p,γ)^99mTc cross sections based on thick target yield measurements are presented and the results are compared with existing data and model calculations. Reaction rates of ⁹²Mo(p,γ)⁹³Tc at temperatures relevant for the γ-process are derived directly from the measured thick target yields. The obtained rates are a factor of 2 lower than the ones used in astrophysical network calculations. It is argued that in the case of fluctuating cross sections the thick target yield measurement can be more suited for a reliable reaction rate determination

[en] The astrophysically important ³He(α,γ)⁷Be reaction was studied at high energies where the available experimental data are in contradiction. A thin window ³He gas cell was used and the cross section was measured with the activation method. The obtained cross sections at energies between E_c.m.=1.5 and 2.5 MeV are compared with the available data and theoretical calculations. The present results support the validity of the high energy cross section energy dependence observed by recent experiments

[en] This study presents the laboratory background measurement of a Clover-type composite γ-detector equipped with a BGO escape-suppression shield. Recently, such a detector had been used in an in-beam γ-spectroscopy measurement of the ¹⁴N(p,γ)¹⁵O reaction deep underground. Here the laboratory γ-ray background of that detector is studied in three different environments: overground, in a shallow underground laboratory and deep underground. In addition, the effect of the escape-suppression shield on the cosmic-ray induced background has been studied in all three cases. The measurements have been performed at LUNA site in the Gran Sasso National Laboratory, Assergi, Italy (deep underground), at the Felsenkeller Laboratory, Dresden, Germany (shallow underground) and ATOMKI, Debrecen, Hungary (Earth's surface).

[en] Complete text of publication follows. The ⁶⁶Ga radioisotope is important e.g. in the high energy efficiency calibration of γ-detectors. Therefore, the precise knowledge of its half-life is crucial. In 2004 a critical review was published about the half-lives of radionuclides considered to be important for detector efficiency calibrations. It was found that the precision of the ⁶⁶Ga half-life is by far not enough for the requirements posed by the International Atomic Energy Agency. Since 2004 two new high precision half-life measurement of ⁶⁶Ga became available whose results disagree by about six standard deviations. This strong deviation indicates that the knowledge of the ⁶⁶Ga half-life is still very far from the required precision, therefore, new experiments are clearly needed. In the present work the half-life of ⁶⁶Ga has been measured based on counting the γ-radiation following the β⁺ decay. Special emphasis was put to the experimental implementation of the measurements to reduce the systematic uncertainties and to increase the reliability of the measured half-life value. Six sources were produced at the cyclotron of Atomki by the ⁶⁶Zn(p,n)⁶⁶Ga and ⁶³Cu(α,n)⁶⁶Ga reactions. Evaporated Zn targets and thick Cu disks were used for these two reactions, respectively. The γ-radiation following the β⁺ decay of ⁶⁶Ga was measured with three shielded HPGe detectors. A sufficiently long waiting time was inserted between the source preparation and the beginning of the counting in order to reduce the initial dead time of the counting setups below 2 %. The reliability of the dead time values provided by the data acquisition system was checked by measuring the decay of one source in parallel with two different acquisition systems. In order to check the longterm stability of the counting systems, longlived reference sources were measured together with the ⁶⁶Ga sources. The reference isotopes were ⁵⁶Co, ⁶⁵Zn and ¹³⁷Cs. The ⁶⁶Ga half-life was determined based on the analysis of the seven strongest γ-transitions. The decay was followed for up to 87 hours (about 9 half-lives) and the spectra were recorded in every 30 minutes. The half-life was determined from the parameters of the exponential curve fitted to the peak area vs. time function. The final value was calculated as the weighted average of 37 individual half-life values (six sources with six or seven γ-transitions). The obtained half-life value is t_1/2 =(9.312±0.032) h. The quoted uncertainty include the statistical uncertainty as well as systematic uncertainties from the stability of the counting systems, dead time determination and peak integration. Further details of the experiments and the data analysis can be found in [5]. The obtained half-life value supports the validity of one of the recent measurements while it is in contradiction with the other one.

[en] The KADoNiS (Karlsruhe Astrophysical Database of Nucleosynthesis in Stars) project is an online database (www.kadonis.org) for cross sections relevant for s-process and the p-process nucleosynthesis. Recently, the p-process part of the KADoNiS database has been extended, and now includes almost all available experimental data from (p, γ), (p, n), (p, α), (α, γ), (α, n) and (α, p) reactions in or close to the respective Gamow window.

[en] Highlights: • Based on gamma-spectroscopy the half-life of 65Ga is measured. • Systematic uncertainties are carefully studied. • The obtained result is (15.133 +- 0.028)min. • This results is in agreement with the only available value in literature, but almost one order of magnitude more precise. - Abstract: The literature half-life value of ⁶⁵Ga is based on only one experiment carried out more than 60 years ago and it has a relatively large uncertainty. In the present work this half-life is determined based on the counting of the γ-rays following the β-decay of ⁶⁵Ga. Our new recommended half-life is t_1/2 = (15.133 ± 0.028) min which is in agreement with the literature value but almost one order of magnitude more precise.

[en] In this paper we describe our experiment determining the half-life of ^133mCe. An activation-based nuclear-reaction cross-section measurement has been carried out for the ¹³⁰Ba(α, n)^133mCe reaction, in order to improve our knowledge of the astrophysical p-process. For the analysis of such a measurement, the precise knowledge of the decay half-life of the reaction product is desired. In the case of ^133mCe the literature half-life value has only been known with a high relative uncertainty. A measurement utilizing γ -spectrometry has been carried out to refine the half-life of ^133mCe. As a result, the new recommended half-life is t_1/2 = (5.326±0.011) h. This value has been found to be consistent with the previous literature value, while its uncertainty has been reduced by more than a factor of 30. (orig.)

[en] In this paper we present the ongoing experiments at ATOMKI related to our systematic γ-process studies. These studies are intended to enlarge the limited experimental database from α-induced reactions on nuclei in the heavier mass range of the γ -process. In all presented cases the activation method was used. The details of the cross section measurements and preliminary results on"1"1"5In(α,n)"1"1"8"mSb, "1"1"5In(α,γ)"1"1"9Sb; "1"6"2Er(α,n)"1"6"5Yb, "1"6"2Er(α,γ)"1"6"6Yb, "1"6"4Er(α,n)"1"6"7Yb, "1"6"6Er(α,n)"1"6"9Yb; "1"9"1Ir(α,n)"1"9"4Au, "1"9"1Ir(α,γ)"1"9"5Au, "1"9"3Ir(α,n)"1"9"6"mAu, "1"9"3Ir(α,n)"1"9"6Au reactions are presented. (paper)