Experimental nuclear physics

Je remercie tout d'abord l'ensemble de l'IPN d'Orsay pour l'accueil durant ces années de thèse. Mes remerciements vont également à Nicola Colonna et Jean-luc Sida, qui ont accepté d'étre les rapporteurs de ce travail malgré le peu de temps qui leur était imparti, et avec qui j'ai pu avoir des discussions approfondies. Et puis merci à Yorick Blumenfeld qui a bien voulu présider le jury au beau milieu de ses déplacements en conférences. Je remercie Katsuhisa Nishio qui a accepté de faire ce long déplacement depuis le Japon pour participer au jury. Je remercie profondément Emmeric Dupont, qui a également accepté d'être membre de ce même jury, et qui a lu très attentivement le manuscrit et apporté de nombreuses corrections pour l'améliorer. Je remercie très profondément, mon directeur de thèse Laurent Tassan-Got qui est le plus sympatique, intelligent, sportif et parfait que j'aie jamais rencontré, avec plein de connaissances pas seulement en physique, mais aussi pour la vie quotidienne. Mes trois années de thèse se sont déroulées dans le groupe PACS dans une excellente ambiance, très sympatique tous les jours. Merci à Laurent Audouin qui m'a aidé pour ma participation à l'expérience en Allemagne et qui s'est beaucoup impliqué dans la correction du manuscrit dans la dernière ligne droite. Merci à Mathieu Lebois qui était toujours disponible pour m'expliquer le fabuleux ROOT, à Jonathon Wilson mon directeur de stage qui m'a attiré dans le domaine de physique nucléaire, à Charles-Olivier Bacri avec ses délicieux chocolats, à Sylvain David le vrai physicien curieux qui ose tenter toutes les activités de 9 ans à 90 ans. Les cris et chants de Baptiste Leniau m'ont marquée pour toujours. Merci pour les dépannages de MCNP avec Baptiste et Marc Ernoult, et pour les café-breaks et breaks après breaks. Merci également à Pierre Halipré, Chloé Gerin (merci pour le thé), Xavier Doligez (le français que je connais au langage le plus rapide tout en étant raffiné) et Hervé Lefort. J'ai énormément apprécié l'ambiance de travail de la collaboration n_TOF, ainsi que tous les membres de cette collaboration, plus particulièrement Frank Gunsing,

The double Penning trap mass spectrometer JYFLTRAP has been employed to measure masses and excitation energies for 11/2 -isomers in 121 Cd, 123 Cd, 125 Cd and 133 Te, for 1/2 -isomers in 129 In and 131 In, and for 7 -isomers in 130 Sn and 134 Sb. These first direct mass measurements of the Cd and In isomers reveal deviations to the excitation energies based on results from beta-decay experiments and yield new information on neutron-and proton-hole states close to 132 Sn. A new excitation energy of 144(4) keV has been determined for 123 Cd m . A good agreement with the precisely known excitation energies of 121 Cd m , 130 Sn m , and 134 Sb m has been found.

The β-feeding probabilities for three important contributors to the decay heat in nuclear reactors, namely 102,104,105 Tc, have been measured using the total absorption spectroscopy technique. For the measurements, sources of very high isobaric purity have been obtained using a Penning trap (JYFLTRAP). A detailed description of the data analysis is given and the results are compared with high-resolution measurements and theoretical calculations.

The n_TOF facility hosts CERN’s pulsed neutron source, comprising two beam lines of different flight paths and one activation station. It is based on a proton beam delivered by the PS accelerator impinging on a lead spallation target. During Long Shutdown 2 (LS2) at CERN (2019-2021), a major upgrade of the spallation target was carried out in order to optimize the performances of the neutron beam. Therefore, the characteristics of n_TOF two experimental areas were investigated in detail. In this work, the focus is on the second experimental area (EAR2), located 20 m above the spallation target. Preliminary results of the neutron energy distribution and beam line energy resolution are presented, compared to previous experimental campaigns and Monte Carlo simulations with the FLUKA code. Moreover, preliminary results of the spatial beam profile measurements are shown.

The n_TOF neutron time-of-flight facility at CERN is used for nuclear data measurements. The n_TOF Collaboration works closely with the Nuclear Reaction Data Centres (NRDC) network to disseminate the experimental data through the international EXFOR library. In addition, the Collaboration helps integrate the results in the evaluated library projects. The present contribution describes the dissemination status of n_TOF results, their impact on evaluated libraries and ongoing efforts to provide n_TOF resonance parameters in ENDF-6 format for further use by evaluation projects.

Neutron-capture reactions on gadolinium isotopes play an important role in several fields of physics,in particular in nuclear Astrophysics for the understanding of the nucleosynthesis of heavy elements (beyond iron) in stars via the s- and r-processes [1] and in nuclear technology. Another important application of gadolinium is linked to the production of terbium, that offers a set of clinically interesting isotopes for theranostics, characterized by complementary physical decay characteristics. In particular, the low-energy β −emitter terbium-161 is very similar to lutetium-177 in terms of half-life (6.89 d), β − energy and chemical properties. Being a significant emitter of conversion/Auger electrons, greater therapeutic effect can therefore be expected in comparison to Lu-177 [2, 3]. For this reason, in the last decade, the study of the neutron capture reaction 160Gd(n,γ)161 Gd and the subsequent β − decay in terbium-161 is getting particular attention. As the nuclear data on the...

Neutron-induced cross sections represent the main nuclear input to models of stellar and Big-Bang nucleosynthesis. While (n,γ) reactions are relevant for the formation of elements heavier than iron, (n,p) and (n,α) reactions can play an important role in specific cases. The time-of-flight method is routinely used at n_TOF to experimentally determine the cross section data. In addition, recent upgrades of the facility will allow the use of activation techniques as well, possibly opening the way to a systematic study of neutron interaction with radioactive isotopes. In the last 20 years n_TOF has provided a large amount of experimental data for Nuclear Astrophysics. Our plan is to carry on challenging measurements and produce nuclear data in the next decades as well.

We have measured the angular distributions of protons corresponding to the ground state transition from the 12C(𝛼, p)15N reaction by varying the energy of 𝛼 particle as wide as possible. We used the large scattering chamber at the Institute for Nuclear Study. Besides 12C, we will also report the results of the targets of 9Be, 23Na, 40A, and 14N. [Summarized from the published Japanese version given on the next page]

The rotational structure of 246 Fm has been investigated using in-beam γ-ray spectroscopic techniques. The experiment was performed using the jurogamii germanium detector array coupled to the gas-filled recoil separator RITU and the GREAT focal plane detection system. Nuclei of 246 Fm were produced using a 186 MeV beam of 40 Ar impinging on a 208 Pb target. The jurogamii array was fully instrumented with TNT2D digital acquisition cards. The use of digital electronics and a rotating target allowed for unprecedented beam intensities of up to 71 particle-nanoamperes for prompt γ-ray spectroscopy at a level of approximately 11 nb. With all these major experimental advances a rotational band is observed for the first time in 246 Fm.

Measurements of the angular distributions of photofission fragments from 238U have been made using bremsstrahlung at end-point energies of 5.8 and 7.2 MeV. Mica strips were used as fragment detectors. The ratio of the quadrupole to dipole fission cross-section was deduced from the measured angular distribution at an end-point energy of 7.2 MeV.

Chapter l describes measurements of cross sections 𝝈(E𝜸) of the 9Be (𝜸, n) reaction with six kinds of radioisotopes. The results were 𝝈(1674.7)=8.8±1.6, 𝝈(1705.2)=13.3±2.4, 𝝈(1724.9)=11.0±2.0, 𝝈(1778.9)=7.3±1.3, 𝝈(1836.0)=4.7±0.9, and 𝝈(2167.6)=1.8±0.4 in units of 10-28cm2. The cross sections measured show a cusp-like peak near the threshold, and its width is narrower than that observed by Jakobson with bremsstrahlung X-rays. Comparison of the present results with theories indicates that mutual agreement is yet qualitative. Chapter 2 describes a measurement of the intensity I(2009.8) of the crossover E4 transition in 46Ti by applying the 9Be (𝜸, n) reaction. The observed intensity per decay of 46Sc was I(2009.8)=(1.2±0.7)×10−7. From the present result, the reduced transition probability B(E4) of the crossover E4 transition between the 2009.8 keV-4+ excited state and the 0+ ground state of 46Ti was estimated as B(E4)=(5.2±t 3.7)×10−99 e2・cm8. The discussion is given about the presently measured intensity and nuclear models. (The text is in Japanese.) (Modified by T. T.)

Neutron cross section measurements are often made relative to a neutron cross section standard. Thus, the accuracy of the neutron standards determines the best possible accuracy of the neutron measurements. The 235U(n,f) cross section is widely used as reference, while it is considered a standard at thermal point and between 0.15 to 200 MeV. For this reason, additional cross section data for the 235U(n,f) reaction are useful in order to improve the accuracy and to extend the energy range of the standard. In this work, preliminary results of the measurement of the 235U(n,f) cross-section relative to the standard 10B(n,a) reaction are presented. The high accuracy measurement was performed at the experimental area EAR-1 of the n_TOF facility at CERN, aiming at covering the energy range from the thermal region up to approximately 100 keV. The samples were produced at JRC-Geel in Belgium, while the experimental setup was based on Micromegas detectors.

This work reports identification of muons by their characteristic lifetime of 2.20 μs after laser-induction of their precursor mesons, both kaons K AE and K 0 L and pions π AE in ultra-dense hydrogen H(0). The pair-production signal from scattered muons at a metal converter in front of a photo-multiplier detector is observed with its decay. The observed signal intensity is decreased by a metal beam-flag which intercepts the meson and muon flux to the detector. Using D(0), the observed decay time is (2.23 AE 0.05) μs in agreement with the free muon lifetime of 2.20 μs. This signal is apparently due to the preferential generation of positive muons. Using p(0), the observed decay time is in the range 1-2 μs, thus shorter than the free muon lifetime, as expected when the signal is mainly caused by negative muons which interact with matter by muon capture.

Linear polarization measurements have been performed for γ-rays in 91 Ru produced with the 58 Ni(36 Ar, 2p1nγ) 91 Ru reaction at a beam energy of 111 MeV. The EXOGAM Ge clover array has been used to measure the γ-γ coincidences, γ-ray linear polarization and γ-ray angular distributions. The polarization sensitivity of the EXOGAM clover detectors acting as Compton polarimeters has been determined in the energy range 0.3−1.3 MeV. Several transitions have been observed for the first time. Measurements of linear polarization and angular distribution have led to the firm assignments of spin differences and parity of high-spin states in 91 Ru. More specifically, calculations using a semi-empirical shell model were performed to understand the structures of the first and second (21/2 +) and (17/2 +) levels. The results are in good agreement with the experimental data, supporting the interpretation of the non yrast (21/2 +) and (17/2 +) states in terms of the Jmax and Jmax − 2 members of the seniority-three ν(g 9/2) −3 multiplet.

This work reports identification of muons by their characteristic lifetime of 2.20 μs after laser-induction of their precursor mesons, both kaons K AE and K 0 L and pions π AE in ultra-dense hydrogen H(0). The pair-production signal from scattered muons at a metal converter in front of a photo-multiplier detector is observed with its decay. The observed signal intensity is decreased by a metal beam-flag which intercepts the meson and muon flux to the detector. Using D(0), the observed decay time is (2.23 AE 0.05) μs in agreement with the free muon lifetime of 2.20 μs. This signal is apparently due to the preferential generation of positive muons. Using p(0), the observed decay time is in the range 1-2 μs, thus shorter than the free muon lifetime, as expected when the signal is mainly caused by negative muons which interact with matter by muon capture.

The n TOF neutron time-of-flight facility at CERN is used for high quality nuclear data measurements from thermal energy up to hundreds of MeV. In line with the CERN open data policy, the n TOF Collaboration takes actions to preserve its unique data, facilitate access to them in standardised format, and allow their re-use by a wide community in the fields of nuclear physics, nuclear astrophysics and various nuclear technologies. The present contribution briefly describes the n TOF outcomes, as well as the status of dissemination and preservation of n TOF final data in the international EXFOR library.

The population of the high-spin states in 140 Nd was investigated using the reaction 96 Zr(48 Ca,4n). The results from two experiments, one with the EUROBALL array and one with the JUROGAM II + RITU + GREAT setup employing the recoil decay tagging technique, have been combined to develop a very detailed level scheme for 140 Nd. Twelve bands of quadrupole transitions and eleven bands of dipole transitions were identified and their connections to low-lying states were established. Calculations using the cranked Nilsson-Strutinsky and the tilted axis cranking models were used to interpret the observed structures. The overall good agreement between the experimental results and the calculations assuming a triaxial shape of the nucleus strongly support the existence of a stable triaxial shape at high spins in this mass region.

The population of the high-spin states in 140 Nd was investigated using the reaction 96 Zr(48 Ca,4n). The results from two experiments, one with the EUROBALL array and one with the JUROGAM II + RITU + GREAT setup employing the recoil decay tagging technique, have been combined to develop a very detailed level scheme for 140 Nd. Twelve bands of quadrupole transitions and eleven bands of dipole transitions were identified and their connections to low-lying states were established. Calculations using the cranked Nilsson-Strutinsky and the tilted axis cranking models were used to interpret the observed structures. The overall good agreement between the experimental results and the calculations assuming a triaxial shape of the nucleus strongly support the existence of a stable triaxial shape at high spins in this mass region.

Using state-of-the-art γ-ray spectroscopic techniques, the first rotational band of a superheavy element, extending up to a spin of 20h, was discovered in the nucleus 256 Rf. To perform such an experiment at the limits of the present instrumentation, several developments were needed. The most important of these developments was of an intense isotopically enriched 50 Ti beam using the MIVOC method. The experimental setup and subsequent analysis allowed the 256 Rf ground-state band to be revealed. The rotational properties of the band are discussed and compared with neighboring transfermium nuclei through the study of their moments of inertia. These data suggest that there is no evidence of a significant deformed shell gap at Z = 104.

Very neutron deficient francium isotopes have been produced in fusion evaporation reactions using 60 Ni ions on 141 Pr targets. The gas-filled recoil separator RITU was employed to collect the fusion products and to separate them from the scattered beam. The activities were implanted into a position sensitive silicon detector after passing through a gas-counter system. The isotopes were identified using spatial and time correlations between the implants and the decays. Two α-particle activities, with E α = 7613(15) keV and T 1/2 = (15 +12 −5) ms and E α = 7684(15) keV and T 1/2 = (16 +13 −5) ms were identified in the new isotope 198 Fr. In addition, the half-life and α-particle energy of 199 Fr were measured with improved precision. The measured decay properties deduced for 199 Fr and 198 Fr suggest that there is an onset of ground-state deformation at N = 112 in the Fr isotopes.

The rotational structure of 246 Fm has been investigated using in-beam γ-ray spectroscopic techniques. The experiment was performed using the jurogamii germanium detector array coupled to the gas-filled recoil separator RITU and the GREAT focal plane detection system. Nuclei of 246 Fm were produced using a 186 MeV beam of 40 Ar impinging on a 208 Pb target. The jurogamii array was fully instrumented with TNT2D digital acquisition cards. The use of digital electronics and a rotating target allowed for unprecedented beam intensities of up to 71 particle-nanoamperes for prompt γ-ray spectroscopy at a level of approximately 11 nb. With all these major experimental advances a rotational band is observed for the first time in 246 Fm.

Using state-of-the-art γ-ray spectroscopic techniques, the first rotational band of a superheavy element, extending up to a spin of 20h, was discovered in the nucleus 256 Rf. To perform such an experiment at the limits of the present instrumentation, several developments were needed. The most important of these developments was of an intense isotopically enriched 50 Ti beam using the MIVOC method. The experimental setup and subsequent analysis allowed the 256 Rf ground-state band to be revealed. The rotational properties of the band are discussed and compared with neighboring transfermium nuclei through the study of their moments of inertia. These data suggest that there is no evidence of a significant deformed shell gap at Z = 104.

Salah satu upaya dalam mengurangi penggunaan pupuk kimia dan usaha meningkatkan unsur hara Nitrogen (N), Pospor (P) dan Kalium (K) adalah dengan penggunaan pupuk organik. Salah satu bahan limbah organik yang mudah ditemui dan dapat berdampak buruk bagi lingkungan jika tidak segera diolah adalah air limbah tahu. Salah satu kekurangan dari air limbah tahu adalah memiliki bau tidak sedap, selain itu menurut Kasman (2018) Limbah cair industri tahu umumnya memiliki derajat keasaman (pH), Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), amoniak, minyak dan lemak, nitrit, dan nitrat yang tinggi. Upaya yang dapat dilakukan untuk mengurangi bau tidak sedap yang dihasilkan dari Pupuk organik cair yang terbuat dari air limbah tahu  adalah dengan menambahkan bahan organik lain. Kurangnya pengetahuan petani/masyarakat sekitar Pabrik Tahu-Tempe skala rumah tangga dalam pengolahan limbah cair pabrik yang dapat menjadi salah satu pendapatan tambahan bagi ...

The advanced time-delayed γ γ (t) method has been applied to determine half-lives of low-lying states in the N = 50 isotones 94 Ru and 96 Pd. The inferred experimental E2 strengths for the 4 + → 2 + transitions in the two nuclei show a dramatic deviation with respect to the shell model predictions in the (f 5/2 ,p,g 9/2) proton hole space in 100 Sn. The anomalous behavior can be ascribed to a breakdown of the seniority quantum number in the πg n 9/2 configuration due to particle-hole excitations across the N = Z = 50 shell as confirmed by large-scale shell model calculations.

The population of the high-spin states in 140 Nd was investigated using the reaction 96 Zr(48 Ca,4n). The results from two experiments, one with the EUROBALL array and one with the JUROGAM II + RITU + GREAT setup employing the recoil decay tagging technique, have been combined to develop a very detailed level scheme for 140 Nd. Twelve bands of quadrupole transitions and eleven bands of dipole transitions were identified and their connections to low-lying states were established. Calculations using the cranked Nilsson-Strutinsky and the tilted axis cranking models were used to interpret the observed structures. The overall good agreement between the experimental results and the calculations assuming a triaxial shape of the nucleus strongly support the existence of a stable triaxial shape at high spins in this mass region.

The population of the high-spin isomers in 139 Nd and 140 Nd was investigated using the 96 Zr(48 Ca,xn) reaction and the JUROGAM + RITU + GREAT setup employing the recoil decay tagging technique. Three transitions feeding the 23/2 + isomer in 139 Nd and two transitions feeding the 20 + isomer in 140 Nd were identified. The newly observed transitions allowed the excitation energy of the isomer to be established in 139 Nd and to assign configurations to the states and bands deexcited by the observed transitions in both nuclei.

The four new neutron deficient isotopes 246 Md (T 1/2 = (1.0 ± 0.4) s), 245 Md (T 1/2 = (0.35 +0.23 −0.16) s), 242 Es (T 1/2 = (16 +6 −4) s) and 241 Es(T 1/2 = (8 +6 −4) s) were produced in fusion reactions of 40 Ar ions with 209 Bi targets at bombarding energies of E p = 4.78, 4.93 and 5.12 A*MeV. The assignment was based on evaporation residue-α-α time and position correlations. A spontaneous fission activity of T 1/2 =(0.90 ± 0.25) ms was observed at a projectile energy of E p = 5.12 A*MeV and assigned to 245 Md.

To support the US Department of Energy Nuclear Criticality Safety Program, neutron-induced cross section experiments were performed at the Geel Electron Linear Accelerator of the Joint Research Center Site Geel, European Union. Neutron capture and transmission measurements were carried out using metallic natural cerium and vanadium samples. Together with existing data, the measured data will be used for a new evaluation and will be submitted with covariances to the ENDF/B nuclear data library.

The high spin states in the N = 80 odd-A 141 Pm nucleus have been investigated by in-beam γ-spectroscopic techniques following the reaction 133 Cs(12 C, 4n) 141 Pm at E = 65 MeV using a modest γ detector array, consisting of seven Compton-suppressed high purity germanium detectors and a multiplicity ball of 14 bismuth germanate elements. Thirty new γ rays have been assigned to 141 Pm on the basis of γ-ray singles and γ γ-coincidence data. The level scheme of 141 Pm has been extended upto an excitation energy of 5.2 MeV and spin 35 2h and 16 new levels have been proposed. Spin-parity assignments for most of the newly proposed levels have been made on the basis of the deduced directional correlation orientation ratios for strong transitions. The meanlives of a few excited states have been determined from the pulsed beam-γ γ coincidence data using the generalised centroid-shift method. The level structure is discussed in the light of known systematics of neighbouring N = 80 isotonic nuclei.

Centre for Crystal Growth, VIT University Vellore, Tamilnadu-632014, INDIA Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, INDIA Saha Institute Nuclear Physics, Kolkata, West Bengal-700064, INDIA Salt Lake, Kolkata, West Bengal-700064, INDIA Nuclear and Radio-analytical Chemistry Section, FChD, MC & MFCG, IGCAR, Kalpakkam-603102, INDIA . * email: kalainathan@yahoo.com

Linear polarization measurements have been performed for γ-rays in 91 Ru produced with the 58 Ni(36 Ar, 2p1nγ) 91 Ru reaction at a beam energy of 111 MeV. The EXOGAM Ge clover array has been used to measure the γ-γ coincidences, γ-ray linear polarization and γ-ray angular distributions. The polarization sensitivity of the EXOGAM clover detectors acting as Compton polarimeters has been determined in the energy range 0.3−1.3 MeV. Several transitions have been observed for the first time. Measurements of linear polarization and angular distribution have led to the firm assignments of spin differences and parity of high-spin states in 91 Ru. More specifically, calculations using a semi-empirical shell model were performed to understand the structures of the first and second (21/2 +) and (17/2 +) levels. The results are in good agreement with the experimental data, supporting the interpretation of the non yrast (21/2 +) and (17/2 +) states in terms of the Jmax and Jmax − 2 members of the seniority-three ν(g 9/2) −3 multiplet.

The (n,f) cross-sections proposed as references by the IAEA for 235 U, 238 U and 209 Bi are compared with a new analysis that combines the measurements performed at CERN-n TOF of their cross-section ratios with new calculations done using Monte Carlo codes based on phenomenological models INCL++, GEMINI++, and ABLA07. The calculations are cross-checked with those for the (p,f) reactions, where experimental values are available. We have evaluated in this way the (n,f) cross sections for 238 U, 235 U and 209 Bi, in the intermediate energy region going from 190 MeV to 2 GeV. Our results definitively discard the JENDL/HE-2007 evaluations above 300 MeV, falling inside the confidence corridor proposed by IAEA but for the points around 300-400 MeV where a discrepancy is to be noticed.

Angular distributions of fission fragments from the neutron-induced fission of 232 Th, 235 U and 238 U have been measured in the energy range 1-200 MeV at the neutron TOF spectrometer GNEIS using position sensitive multiwire proportional counters as fission fragment detector. A description of the experimental setup and measurement procedure are presented. The anisotropy of fission fragments deduced from the data on measured angular distributions is presented in comparison with experimental data of other authors.

233U is of key importance among the fissile nuclei in the Th-U fuel cycle. A particularity of 233U is its small neutron capture cross-section, which is on average about one order of magnitude lower than the fission cross-section. The accuracy in the measurement of the 233U capture cross-section depends crucially on an efficient capture-fission discrimination, thus a combined set-up of fission and γ-detectors is needed. A measurement of the 233U capture cross-section and capture-to-fission ratio was performed at the CERN n_TOF facility. The Total Absorption Calorimeter (TAC) of n_TOF was employed as γ-detector coupled with a novel compact ionization chamber as fission detector. A brief description of the experimental set-up will be given, and essential parts of the analysis procedure as well as the preliminary response of the set-up to capture are presented and discussed.

The 33 S(n,α) 30 Si cross section measurement, using 10 B(n,α) as reference, at the n TOF Experimental Area 2 (EAR2) facility at CERN is presented. Data from 0.01 eV to 100 keV are provided and, for the first time, the cross section is measured in the range from 0.01 eV to 10 keV. These data may be used for a future evaluation of the cross section because present evaluations exhibit large discrepancies. The 33 S(n,α) 30 Si reaction is of interest in medical physics because of its possible use as a cooperative target to boron in Neutron Capture Therapy (NCT).

233U is the fissile nuclei in the Th-U fuel cycle with a particularily small neutron capture cross setion which is on average about one order of magnitude lower than its fission cross section. Hence, the measurement of the 233U(n, γ) cross section relies on a method to accurately distinguish between capture and fission γ-rays. A measurement of the 233U α-ratio has been performed at the n_TOF facility at CERN using a so-called fission tagging setup, coupling n_TOF 's Total Absorption Calorimeter with a novel fission chamber to tag the fission γ-rays. The experimental setup is described and essential parts of the analysis are discussed. Finally, a preliminary 233U α-ratio is presented.

The n TOF neutron time-of-flight facility at CERN is used for high quality nuclear data measurements from thermal energy up to hundreds of MeV. In line with the CERN open data policy, the n TOF Collaboration takes actions to preserve its unique data, facilitate access to them in standardised format, and allow their re-use by a wide community in the fields of nuclear physics, nuclear astrophysics and various nuclear technologies. The present contribution briefly describes the n TOF outcomes, as well as the status of dissemination and preservation of n TOF final data in the international EXFOR library.

The accurate calculations of neutron-induced reaction cross sections are relevant for many nuclear applications. The photon strength functions and nuclear level densities are essential inputs for such calculations. These quantities for 235U are studied using the measurement of the gamma de-excitation cascades in radiative capture on 234U with the Total Absorption Calorimeter at n_TOF at CERN. This segmented 4π gamma calorimeter is designed to detect gamma rays emitted from the nucleus with high efficiency. This experiment provides information on gamma multiplicity and gamma spectra that can be compared with numerical simulations. The code DICEBOXC is used to simulate the gamma cascades while GEANT4 is used for the simulation of the interaction of these gammas with the TAC materials. Available models and their parameters are being tested using the present data. Some preliminary results of this ongoing study are presented and discussed.