The semi-magic nuclei 138 Ba, 140 Ce, and 144 Sm have been investigated in photon scattering experiments up to an excitation energy of about 10 MeV. The distribution of the electric dipole strength shows a resonance like structure at energies between 5.5 and 8 MeV exhausting up to 1 % of the isovector E1 Energy Weighted Sum Rule.

The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [1] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [2]. In this paper, we document the current state of all completed beamline components (as of the first neutrino mass measurement campaign), demonstrate our ability to reliably and stably control them over long times, and present details on their respective commissioning campaigns. K: Beam-line instrumentation (beam position and profile monitors, beam-intensity monitors, bunch length monitors); Spectrometers; Gas systems and purification; Neutrino detectors A X P : 2103.04755Neutrino-mass mode. This is the standard mode of operation to continually adjust the retarding voltage of the MS in the range of [ 0 − 40 eV; 0 + 50 eV] while tritium is in the system. This scanning range can be adjusted if required. The voltage and the time spent at each setting are defined by the Measurement Time Distribution (MTD) (figure 3). A typical run at a given voltage lasts between 20 s and 600 s; a full scan of the energy range given above takes about 2 h. Of these standard neutrino-mass runs, a small portion will be dedicated to sterile neutrino searches. These searches involve scanning much farther (order of keV) below the endpoint 0 .Calibration mode. To check the long-term system stability, calibration measurements are done regularly. The neutrino-mass mode is suspended for the duration of these measurement:• An energy calibration of the FPD (section 6) is performed weekly, which requires closing off the detector system from the main beamline for about 4 h.• The offset and the gain correction factor of the low-voltage readout in the high-voltage measurement chain needs to be calibrated based on standard reference sources (section 5.3.4). This requires stopping the precision monitoring of the MS retarding potential twice per week for about 0.5 h each.

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The nucleosynthesis of heavy proton-rich nuclei in a stellar photon bath at temperatures of the astrophysical γ-process was investigated where the photon bath was simulated by the superposition of bremsstrahlung spectra with different endpoint energies. The method was applied to derive (γ,n) cross sections and reaction rates for several platinum isotopes.PACS numbers: 26.30.+k, 98.80.Ft, 26.45.+h The trans-iron nuclei have been synthesized by neutron capture in the s-and r-processes, except the p-nuclei (p for proton-rich), with relative abundances of the order of 0.01 to 1% [1]. The main production mechanism of the p-nuclei is assumed to be photodisintegration in the γ-process, i.e. by (γ,n), (γ,p), and (γ,α) reactions induced on heavier seed nuclei synthesized in the s-and r-processes. Typical parameters for the γ-process are temperatures of 2 ≤ T 9 ≤ 3 (T 9 is the temperature in units of 10 9 K), densities ρ ≈ 10 6 g/cm 3 , and time scales τ in the order of seconds. Several astrophysical sites for the γ-process have been proposed, whereby the oxygenand neon-rich layers of type II supernovae seem to be good candidates. However, no definite conclusions have been reached yet [1], predominantly due to the lack of experimental data for the cross sections and reaction rates of the γ-induced reactions at astrophysically relevant energies. All reaction rates have been derived theoretically using statistical model calculations [1-6].The energy distribution of a thermal photon bath at a temperature T is given by the Planck distributionwhere n γ (E, T ) is the number of γ-rays at energy E per unit of volume and energy interval. In a photon-induced reaction B(γ,x)A the distribution leads to a temperature dependent decay rate λ(T ) of the initial nucleus Bwith the speed of light c and the cross section of the γ-induced reaction σ (γ,x) (E). Obviously, λ is also the production rate of the residual nucleus A. In the following we will focus on photodisintegration by the (γ,n) reactions. A large number of (γ,n) cross sections has been measured over the years [7,8]. However, most of the data have been obtained around the giant dipole resonance (GDR), i.e. at energies much higher than those in stars, and practically no data exist for the p-nuclei. The integrand in Eq. (2) is given by the product of the γ flux c n γ (E, T ), which decreases steeply with increasing energy E, and the cross section σ (γ,x) (E), which increases with E approaching the GDR region. The product leads then to a window at an effective energy E eff with a width ∆ similar to the Gamow window for charged-particle-induced reactions. If one assumes a typical threshold behavior of the (γ,n) cross section close to the threshold energy E thr , the effective energy is approximately given by E eff = E thr + 1 2 kT , and the typical width ∆ is in the order of 1 MeV (Fig. 1). 191 Pt reaction (E thr = 8676 keV) in a thermal photon bath with temperature T9 = 2.5. The Planck distribution nγ (E, T ) (dotted line) and the (γ,n) cross section σ(E) (dashed line) are giv...