Refine
Year of publication
Document Type
- Article (1903)
- Preprint (1278)
- Doctoral Thesis (596)
- Conference Proceeding (248)
- diplomthesis (101)
- Bachelor Thesis (75)
- Master's Thesis (61)
- Contribution to a Periodical (46)
- Book (33)
- Diploma Thesis (33)
Keywords
- Kollisionen schwerer Ionen (47)
- heavy ion collisions (44)
- LHC (25)
- Quark-Gluon-Plasma (25)
- Heavy Ion Experiments (20)
- equation of state (19)
- quark-gluon plasma (19)
- BESIII (17)
- Relativistic heavy-ion collisions (16)
- QCD (15)
Institute
- Physik (4469) (remove)
The total charm-quark production cross section per unit of rapidity dσ(cc)/dy, and the fragmentation fractions of charm quarks to different charm-hadron species f(c → hc), are measured for the first time in p–Pb collisions at √sNN = 5.02 TeV at midrapidity (−0.96 < y < 0.04 in the centre-ofmass frame) using data collected by ALICE at the CERN LHC. The results are obtained based on all the available measurements of prompt production of ground-state charm-hadron species: D0, D+,D+s, and J/ψ mesons, and Λ+cand Ξ0cbaryons. The resulting cross section is dσ(cc)/dy = 219.6±6.3 (stat.)+10.5−11.8(syst.)+7.6−2.9(extr.)±5.4 (BR)±4.6 (lumi.)±19.5 (rapidity shape) +15.0 (Ω0c) mb, which is consistent with a binary scaling of pQCD calculations from pp ollisions. The measured fragmentation fractions are compatible with those measured in pp collisions at √s = 5.02 and 13 TeV, showing an increase in the relative production rates of charm baryons with respect to charm mesons in pp and p–Pb collisions compared with e+e − and e−p collisions. The pT-integrated nuclear modification factor of charm quarks, RpPb(cc) = 0.91±0.04 (stat.) +0.08 −0.09 (syst.) +0.04 −0.03 (extr.)±0.03 (lumi.), is found to be consistent with unity and with theoretical predictions including nuclear modifications of the parton distribution functions.
The e+e−→D+sDs1(2536)− and e+e−→D+sD∗s2(2573)− processes are studied using data samples collected with the BESIII detector at center-of-mass energies from 4.530 to 4.946~GeV. The absolute branching fractions of Ds1(2536)−→D¯∗0K− and D∗s2(2573)−→D¯0K− are measured for the first time to be (35.9±4.8±3.5)% and (37.4±3.1±4.6)%, respectively. The measurements are in tension with predictions based on the assumption that the Ds1(2536) and D∗s2(2573) are dominated by a bare cs¯ component. The e+e−→D+sDs1(2536)− and e+e−→D+sD∗s2(2573)− cross sections are measured, and a resonant structure at around 4.6~GeV with a width of 50~MeV is observed for the first time with a statistical significance of 15σ in the e+e−→D+sD∗s2(2573)− process. It could be the Y(4626) found by the Belle collaboration in the D+sDs1(2536)− final state, since they have similar masses and widths. There is also evidence for a structure at around 4.75~GeV in both processes.
The family of cubic noncentrosymmetric 3-4-3 compounds has become a fertile ground for the discovery of novel correlated metallic and insulating phases. Here, we report the synthesis of a new heavy fermion compound, Ce3Bi4Ni3. It is an isoelectronic analog of the prototypical Kondo insulator Ce3Bi4Pt3 and of the recently discovered Weyl-Kondo semimetal Ce3Bi4Pd3. In contrast to the volume-preserving Pt-Pd substitution, structural and chemical analyses reveal a positive chemical pressure effect in Ce3Bi4Ni3 relative to its heavier counterparts. Based on the results of electrical resistivity, Hall effect, magnetic susceptibility, and specific heat measurements, we identify an energy gap of 65-70 meV, about eight times larger than that in Ce3Bi4Pt3 and about 45 times larger than that of the Kondo-insulating background hosting the Weyl nodes in Ce3Bi4Pd3. We show that this gap as well as other physical properties do not evolve monotonically with increasing atomic number, i.e., in the sequence Ce3Bi4Ni3-Ce3Bi4Pd3-Ce3Bi4Pt3, but instead with increasing partial electronic density of states of the d orbitals at the Fermi energy. To understand under which condition topological states form in these materials is a topic for future studies.
Heterostructures of graphene in proximity to magnetic insulators open the possibility to investigate exotic states emerging from the interplay of magnetism, strain and charge transfer between the layers. Recent reports on the growth of self-integrated atomic wires of β-RuCl3 on graphite suggest these materials as versatile candidates to investigate these effects. Here we present detailed first principles calculations on the charge transfer and electronic structure of β-RuCl3/heterostructures and provide a comparison with the work function analysis of the related honeycomb family members α-RuX3 (X = Cl,Br,I). We find that proximity of the two layers leads to a hole-doped graphene and electron-doped RuX3 in all cases, which is sensitively dependent on the distance between the two layers. Furthermore, strain effects due to lattice mismatch control the magnetization which itself has a strong effect on the charge transfer. Charge accumulation in β-RuCl3 strongly drops away from the chain making such heterostructures suitable candidates for sharp interfacial junctions in graphene-based devices.
canning tunneling microscopy (STM) is perhaps the most promising way to detect the superconducting gap size and structure in the canonical unconventional superconductor Sr2RuO4 directly. However, in many cases, researchers have reported being unable to detect the gap at all in simple STM conductance measurements. Recently, an investigation of this issue on various local topographic structures on a Sr-terminated surface found that superconducting spectra appeared only in the region of small nanoscale canyons, corresponding to the removal of one RuO surface layer. Here, we analyze the electronic structure of various possible surface structures using first principles methods, and argue that bulk conditions favorable for superconductivity can be achieved when removal of the RuO layer suppresses the RuO4 octahedral rotation locally. We further propose alternative terminations to the most frequently reported Sr termination where superconductivity surfaces should be observed.
Motivated by recently reported magnetic-field induced topological phases in ultracold atoms and correlated Moiré materials, we investigate topological phase transitions in a minimal model consisting of interacting spinless fermions described by the Hofstadter model on a square lattice. For interacting lattice Hamiltonians in the presence of a commensurate magnetic flux it has been demonstrated that the quantized Hall conductivity is constrained by a Lieb-Schultz-Mattis (LSM)-type theorem due to magnetic translation symmetry. In this work, we revisit the validity of the theorem for such models and establish that a topological phase transition from a topological to a trivial insulating phase can be realized but must be accompanied by spontaneous magnetic translation symmetry breaking caused by charge ordering of the spinless fermions. To support our findings, the topological phase diagram for varying interaction strength is mapped out numerically with exact diagonalization for different flux quantum ratios and band fillings using symmetry indicators. We discuss our results in the context of the LSM-type theorem.
Motivated by the on-going discussion on the nature of magnetism in the quantum Ising chain CoNb2O6, we present a first-principles-based analysis of its exchange interactions by applying an \textit{ab initio} approach with additional modelling that accounts for various drawbacks of a purely density functional theory ansatz. With this method we are able to extract and understand the origin of the magnetic couplings under inclusion of all symmetry-allowed terms, and to resolve the conflicting model descriptions in CoNb2O6. We find that the twisted Kitaev chain and the transverse-field ferromagnetic Ising chain views are mutually compatible, although additional off-diagonal exchanges are necessary to provide a complete picture. We show that the dominant exchange interaction is a ligand-centered exchange process - involving the eg electrons -, which is rendered anisotropic by the low-symmetry crystal fields environments in CoNb2O6, giving rise to the dominant Ising exchange, while the smaller bond-dependent anisotropies are found to originate from d−d kinetic exchange processes involving the t2g electrons. We demonstrate the validity of our approach by comparing the predictions of the obtained low-energy model to measured THz and inelastic neutron scattering spectra.
he family of cubic noncentrosymmetric 3-4-3 compounds has become a fertile ground for the discovery of novel correlated metallic and insulating phases. Here, we report the synthesis of a new heavy fermion compound, Ce3Bi4Ni3. It is an isoelectronic analog of the prototypical Kondo insulator Ce3Bi4Pt3 and of the recently discovered Weyl-Kondo semimetal Ce3Bi4Pd3. In contrast to the volume-preserving Pt-Pd substitution, structural and chemical analyses reveal a positive chemical pressure effect in Ce3Bi4Ni3 relative to its heavier counterparts. Based on the results of electrical resistivity, Hall effect, magnetic susceptibility, and specific heat measurements, we identify an energy gap of 65–70 meV, about eight times larger than that in Ce3Bi4Pt3 and about 45 times larger than that of the Kondo-insulating background hosting the Weyl nodes in Ce3Bi4Pd3. We show that this gap as well as other physical properties do not evolve monotonically with increasing atomic number, i.e., in the sequence Ce3Bi4Ni3−Ce3Bi4Pd3−Ce3Bi4Pt3, but instead with increasing partial electronic density of states of the 𝑑 orbitals at the Fermi energy. This work opens the possibility to investigate the conditions under which topological states develop in this series of strongly correlated 3-4-3 materials.
Using a sample of (10087±44)×106 𝐽/𝜓 events, which is about 45 times larger than that was previously analyzed, a further investigation on the 𝐽/𝜓→𝛾3(𝜋+𝜋−) decay is performed. A significant distortion at 1.84 GeV/𝑐2 in the line shape of the 3(𝜋+𝜋−) invariant mass spectrum is observed for the first time, which could be resolved by two overlapping resonant structures, 𝑋(1840) and 𝑋(1880). The new state 𝑋(1880) is observed with a statistical significance larger than 10𝜎. The mass and width of 𝑋(1880) are determined to be 1882.1±1.7±0.7 MeV/𝑐2 and 30.7±5.5±2.4 MeV, respectively, which indicates the existence of a 𝑝¯ 𝑝 bound state.
Using data samples collected with the BESIII detector operating at the BEPCII storage ring, the cross section of the inclusive process e+e−→η+X, normalized by the total cross section of e+e−→hadrons, is measured at eight center-of-mass energy points from 2.0000 GeV to 3.6710 GeV. These are the first measurements with momentum dependence in this energy region. Our measurement shows a significant discrepancy from calculations with the existing fragmentation functions. To address this discrepancy, a new QCD analysis is performed at the next-to-next-to-leading order with hadron mass corrections and higher twist effects, which can explain both the established high-energy data and our measurements reasonably well.
The process 𝑒+𝑒−→Σ+¯Σ− is studied from threshold up to 3.04 GeV/𝑐2 via the initial-state radiation technique using data with an integrated luminosity of 12.0 fb−1, collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at the BEPCII collider. The pair production cross sections and the effective form factors of Σ are measured in eleven Σ+¯Σ− invariant mass intervals from threshold to 3.04 GeV/𝑐2. The results are consistent with the previous results from Belle and BESIII. Furthermore, the branching fractions of the decays 𝐽/𝜓→Σ+¯Σ− and 𝜓(3686)→Σ+¯Σ− are determined and the obtained results are consistent with the previous results of BESIII.
Bounding Dark Energy from the SPARC rotation curves: Data driven probe for galaxy virialization
(2024)
Dark Energy (DE) acts as a repulsive force that opposes gravitational attraction. Assuming galaxies maintain a steady state over extended periods, the estimated upper bound on DE studies its resistance to the attractive gravitational force from dark matter. Using the SPARC dataset, we fit the Navarro-Frenk-White (NFW) and Hernquist models to identify the most suitable galaxies for these models. Introducing the presence of DE in these galaxies helps establish the upper limit on its repulsive force. This upper bound on DE sits around ρ(<Λ)∼10−25~kg/m3, only two orders of magnitude higher than the one measured by Planck. We discuss the conditions for detecting DE in different systems and show the consistency of the upper bound from galaxies to other systems. The upper bound is of the same order of magnitude as ρ200=200ρc for both dark matter profiles. We also address the implications for future measurements on that upper bound and the condition for detecting the impact of Λ on galactic scales.
The production cross section of inclusive isolated photons has been measured by the ALICE experiment at the CERN LHC in pp collisions at centre-of-momentum energy of s√=13 TeV collected during the LHC Run 2 data-taking period. The measurement is performed by combining the measurements of the electromagnetic calorimeter EMCal and the central tracking detectors ITS and TPC, covering a pseudorapidity range of |ηγ|<0.67 and a transverse momentum range of 7<pγT<200 GeV/c. The result extends to lower pγT and xγT=2pγT/s√ ranges, the lowest xγT of any isolated photon measurements to date, extending significantly those measured by the ATLAS and CMS experiments towards lower pγT at the same collision energy with a small overlap between the measurements. The measurement is compared with next-to-leading order perturbative QCD calculations and the results from the ATLAS and CMS experiments as well as with measurements at other collision energies. The measurement and theory prediction are in agreement with each other within the experimental and theoretical uncertainties.
This short paper gives a brief overview of the manifestly covariant canonical gauge gravity (CCGG) that is rooted in the De Donder-Weyl Hamiltonian formulation of relativistic field theories, and the proven methodology of the canonical transformation theory. That framework derives, from a few basic physical and mathematical assumptions, equations describing generic matter and gravity dynamics with the spin connection emerging as a Yang Mills-type gauge field. While the interaction of any matter field with spacetime is fixed just by the transformation property of that field, a concrete gravity ansatz is introduced by the choice of the free (kinetic) gravity Hamiltonian. The key elements of this approach are discussed and its implications for particle dynamics and cosmology are presented. New insights: Anomalous Pauli coupling of spinors to curvature and torsion of spacetime, spacetime with (A)dS ground state, inertia, torsion and geometrical vacuum energy, Zero-energy balance of the Universe leading to a vanishing cosmological constant and torsional dark energy.
The dynamics of the torsion field is analyzed in the framework of the Covariant Canonical Gauge Theory of Gravity (CCGG), a De Donder–Weyl Hamiltonian formulation of gauge gravity. The action is quadratic in both, the torsion and the Riemann–Cartan tensor. Since the latter adds the derivative of torsion to the equations of motion, torsion is no longer identical to spin density, as in the Einstein–Cartan theory, but an additional propagating degree of freedom. As torsion turns out to be totally anti-symmetric, it can be parametrised via a single axial vector. It is shown in this paper that, in the weak torsion limit, the axial vector obeys a wave equation with an effective mass term which is partially dependent on the scalar curvature. The source of torsion is thereby given by the fermion axial current which is the net fermionic spin density of the system. Possible measurable effects and approaches to experimental analysis are addressed. For example, neutron star mergers could act as a dipoles or quadrupoles for torsional radiation, and an analysis of radiation of pulsars could lead to a detection of torsion wave background radiation.
Experimental data from the NA49 collaboration show an unexpectedly steep rise of the rapidity width of the ϕ meson as function of beam energy, which was suggested as possible interesting signal for novel physics. In this work we show that the Ultra-relativistic Quantum-Molecular-Dynamics (UrQMD) model is able to reproduce the shapes of the rapidity distributions of most measured hadrons and predicts a common linear increase of the width for all hadrons. Only when following the exact same analysis technique and experimental acceptance of the NA49 and NA61/SHINE collaborations, we find that the extracted value of the rapidity width of the ϕ increases drastically for the highest beam energy. We conclude that the observed steep increase of the ϕ rapidity width is a problem of limited detector acceptance and the simplified Gaussian fit approximation.
In dieser Dissertation werden die Erfahrungen mit verschiedenen Präparationsmethoden für CH-Kavitäten beschrieben, um die Leistung der Kavitäten nach der Herstellung weiter zu steigern. Die Leistung wird anhand von zwei wichtigen HF-Parametern bewertet:
dem elektrischen Feld Ea und der intrinsischen Güte Q0. Im Gegensatz zu normalleitenden (NC) Kavitäten kann die intrinsische Güte von supraleitenden (SC) Kavitäten mit zunehmendem elektrischem Feld erheblich variieren. Das optimale Ergebnis für die Kavitätenpräparation ist die Erhöhung des maximalen elektrischen Feldes unter Beibehaltung eines höheren Q0 über die gesamte Feldspanne. Da Q0 umgekehrt proportional zu den Kavitätsverlusten ist, reduziert eine Erhöhung des Qualitätsfaktors die Kryoverluste für den Betrieb bei gegebenem Feldniveau. Die Entwicklung der Kavitätenperformanz im Verlauf dieser Arbeit dargestellt.
Die meisten SC-Kavitäten sind elliptische Strukturen, welche bei hoher Geschwindigkeit und Tastrate angewendet werden. Die Präparationsmethoden wurden daher überwiegend auf diese Strukturen angewandt und optimiert. Diese Arbeit konzentriert sich auf die Umsetzung der zuverlässigsten und vielversprechendsten Oberflächenbehandlungen mittels des ersten vom IAP entwickelten SC 360MHz CH-Prototyps. Diese Kavität wies nach 11 Jahren Lagerung eine verminderte Leistung auf, welche mit Röntgenstrahlung bei bereits niedrigen elektrischen Feldern einherging. Dies deutet auf eine unbeabsichtigte Belüftung mit normaler Luft hin, durch die Partikel eingeführt wurden, die als verstärkende Quellen von Elektronen fungierten. Außerdem musste der Leistungskoppler aufgrund einer starken Überkopplung neu ausgelegt werden.
Die Kavität wurde für 48 Stunden bei 120◦ C mittels Heizbändern in der Experimentierhalle des IAP’s ausgeheizt, was zu einer Verbesserung des Qualitätsfaktors bei niedrigen Werten und zu einer Verkürzung der für die Konditionierung von Multipacting-Barrieren erforderlichen Zeit führte. Allerdings wurde durch diese Behandlung das maximale erreichbare elektrische Feld weiter verringert. Die Verbesserung der Güte ist auf das Ausgasen der Kohlenwasserstoffe während des Backvorgangs zurückzuführen. Die negative Auswirkung auf das maximale elektrische Feld ist weniger auf das Backen selbst zurückzuführen als auf den Transport der Kavität und die verwendeten Vakuumkomponenten, die in der Versuchshalle gelagert sind.
Die beobachtete Leistungseinschränkung lässt sich hauptsächlich durch Partikel im Inneren des Resonators erklären, da Feldemission bei niedrigen Feldstärken auftrat. Eine Hochdruckspülung mit ultrareinem Wasser (HPR) ist das Standardverfahren, um nach Behandlungen, bei denen das Risiko einer Oberflächenkontamination besteht, eine hohe Reinheit der inneren Oberflächen zu erreichen. Die HPR wurde in Zusammenarbeit mit dem Helmholtz-Institut-Mainz und der Gesellschaft für Schwerionenforschung geplant und durchgeführt. Der Resonator zeigte bereits während der Messung der Q-E-Kurve eine Zunahme der transmittierten Leistung bei konstanter Vorwärtsleistung, was vor der HPR nicht der Fall war. Bei der CW-HF-Konditionierung zeigte die Kavität den höchsten Gradienten bei einem deutlich schwächeren Q-Abfall bei hohen Feldstärken.
Sowohl bei der Messung von 2008 als auch bei der beschriebenen Messung wurde die Kavität mit einer HPR-Behandlung fertiggestellt, aber für die HPR-Behandlung bei HIM in Mainz wurden einige Anpassungen vorbereitet. Der CH Prototyp verfügt über keine zusätzlichen Spülports und wurde daher mit zwei verschiedenen Düsen mit unterschiedlichen Sprühwinkeln gespült, um die erreichbaren inneren Resonatorflächen zu maximieren. Die Verwendung mehrerer Sprühwinkel könnte auch für CH-Kavitäten mit Spülöffnungen von Vorteil sein und sollte für zukünftige HPR-Anwendungen in Betracht gezogen werden.
Die Heliumbehandlung wurde am CH-Prototyp 2,5 Stunden lang durchgeführt und lieferte vielversprechende Ergebnisse in Bezug auf die Güte und die Gradientenoptimierung.
Während dieses Prozesses wurde die emittierte Röntgenstrahlung in Richtung am Arbeitsplatzs gemessen und zeigte starke zeitabhängige Fluktuationen. Dies deutete auf die Beseitigung von Partikeln hin und wurde anschließend durch einen Anstieg des elektrischen Feldes von 8,4 auf 8,7 MV/m bestätigt. Eine unerwartete Auswirkung wurde bei der Q-Steigung im mittleren bis hohen Feld festgestellt, bei der der Qualitätsfaktor im Vergleich zum HF-konditionierten Fall eine Erhöhung von 5% oberhalb von 2MV/m aufwies. Dieser systematische Anstieg wurde für diesen Beschleuniger vor der Behandlung bisher nicht beobachtet. Stickstoffgedopte Kavitäten zeigen ein ähnliches Verhalten, bei dem Wechselwirkungen innerhalb der Oxidschicht mit Änderungen der Qualitätsfaktoren korreliert sind. Da Helium ein nicht reaktives Element ist, sind mögliche Erklärungen für diesen Effekt der Sputterprozess und die Einlagerung von Helium innerhalb der Oberfläche. Eine Serie von Heliumbehandlungen ist geplant, um ein optimiertes und sicheres Rezept für CH-Kavitäten zu finden. Die Q-E-Messung nach der Abkühlung und vor der Behandlung wird auch zeigen, ob der Leistungsgewinn durch ein Aufwärmen auf Raumtemperatur beeinträchtigt wird.
Die in dieser Arbeit skizzierte Behandlungssequenz wird für CH-Kavitäten dringend empfohlen. Das Ausheizen hat sich bei der Verringerung des Multipactings and der Güteabnahme bei hohen Feldern als wirksam erwiesen und bleibt von der anschließenden HPR unbeeinflusst. In dieser Arbeit wurden keine negativen Auswirkungen der HPR auf das Multipactingverhalten festgestellt. Anschließend wird eine CW-HF-Konditionierung durchgeführt, bis keine weitere Leistungszunahme der Kavität mehr zu verzeichnen ist.
Wenn die Kavität immer noch durch Feldemission begrenzt ist, sollte eine Wiederholung der HPR-Behandlung in Betracht gezogen werden, da bei sorgfältiger Durchführung der HPR keine der bisherig gefertigten CH-Kavitäten hierdurch begrenzt war. Es ist auch anzumerken, dass die Heliumbehandlung nur an der 360MHz CH-Kavität durchgeführt wurde, als diese eine geringe Strahlung durch Feldemission aufwies. Das Risiko des Heliumprocessing an CH-Kavitäten unter starker Feldemission ist unbekannt. Es ist zu erwarten, dass die Elektronenströme und damit die Ionenbeschusslawinen zunehmen und ein größeres Risiko für die Beschädigung von der Komponenten darstellen. Nach dem derzeitigen Kenntnisstand sollte die Heliumbehandlung nur für gut vorbereitete Kavitäten mit minimaler Feldemission in Betracht gezogen werden.
The PhD addresses the feasibility of reconstructing open charm mesons with the Compressed Baryonic Matter experiment, which will be installed at the FAIR accelerator complex at Darmstadt/Germany. The measurements will be carried out by means of a dedicated Micro Vertex Detector (MVD), which will be equipped with CMOS Monolithic Active Pixel Sensors (MAPS). The feasibility of reconstructing the particles with a proposed detector setup was studied.
To obtain conclusive results, the properties of a MAPS prototype were measured in a beam test at the CERN-SPS accelerator. Based on the results achieved, a dedicated simulation software for the sensors was developed and implemented into the software framework of CBM (CBMRoot). Simulations on the reconstruction of D0-mesons were carried out. It is concluded that the reconstruction of those particles is possible.
The PhD introduces the physics motivation of doing open charm measurements, represents the results of the measurements of MAPS and introduces the innovative simulation model for those sensors as much as the concept and results of simulations of the D0 reconstruction.
Most elements heavier than iron are synthesized in stars during neutron capture reactions in the r- and s-process. The s-process nucleosynthesis is composed of the main and weak component. While the s-process is considered to be well understood, further investigations using nucleosynthesis simulations rely on measured neutron capture cross sections as crucial input parameters. Neutron capture cross sections
relevant for the s-process can be measured using various experimental methods. A prominent example is the activation method relying on the 7Li(p,n)7Be reaction as a neutron source, which has the advantage of high neutron intensities and is able to create a quasi-stellar neutron spectrum at kBT = 25 keV. Other neutron sources able to provide quasi-stellar spectra at different energies suffer from lower neutron intensities. Simulations using the PINO tool suggest the neutron activation of samples with different neutron spectra, provided by the 7Li(p,n)7Be reaction, and a subsequent linear combination of the obtained spectrum-averaged cross sections
to determine the Maxwellian-averaged cross section (MACS) at various energies of astrophysical relevance. To investigate the accuracy of the PINO tool at proton energies between the neutron emission threshold at Ep = 1880.4 keV and 2800 keV,
measurements of the 7Li(p,n)7Be neutron fields are presented, which were carried out at the PTB Ion Accelerator Facility at the Physikalisch-Technische Bundesanstalt in Braunschweig. The neutron fields of ten different proton energies were measured.
The presented neutron fields show a good agreement at proton energies Ep = 1887, 1897, 1907, 1912 and 2100 keV. For the other proton energies, E p = 2000, 2200, 2300, 2500, and 2800 keV, differences between measurement and simulation were found and discussed. The obtained results can be used to benchmark and adapt the PINO tool and provide crucial information for further improvement of the neutron activation method for astrophysics.
An application for the 7Li(p,n)7Be neutron fields is presented as an activation experiment campaign of gallium, an element that is mostly produced during the weak s-process in massive stars. The available cross section data for the 69,71Ga(n,γ)
reactions, mostly determined by activation measurements, show differences up toa factor of three. To improve the data situation, activation measurements were carried out using the 7Li(p,n)7Be reaction. The neutron capture cross sections for
a quasi-stellar neutron spectrum at kBT = 25 keV were determined for 69Ga and 71Ga.