The new technology of laser-driven ion acceleration (LDA) has shown the potential for driving highly brilliant particle beams. Laser-driven ion acceleration differs from conventional proton sources ...by its ultra-high dose rate, whose radiobiological impact should be investigated thoroughly before adopting current clinical dose concepts. The growth of human FaDu tumors transplanted onto the hind leg of nude mice was measured sonographically. Tumors were irradiated with 20 Gy of 23 MeV protons at pulsed mode with single pulses of 1 ns duration or continuous mode (∼100 ms) in comparison to controls and to a dose-response curve for 6 MV photons. Tumor growth delay and the relative biological effectiveness (RBE) were calculated for all irradiation modes. The mean target dose reconstructed from Gafchromic films was 17.4 ± 0.8 Gy for the pulsed and 19.7 ± 1.1 Gy for the continuous irradiation mode. The mean tumor growth delay was 34 ± 6 days for pulsed, 35 ± 6 days for continuous protons, and 31 ± 7 days for photons 20 ± 1.2 Gy, resulting in RBEs of 1.22 ± 0.19 for pulsed and 1.10 ± 0.18 for continuous protons, respectively. In summary, protons were found to be significantly more effective in reducing the tumor volume than photons (P < 0.05). Together with the results of previous in vitro experiments, the in vivo data reveal no evidence for a substantially different radiobiology that is associated with the ultra-high dose rate of protons that might be generated from advanced laser technology in the future.
Abstract
Investigations of neutron-rich nuclei, particularly those that lie in regions of the nuclear chart known for a high probability of isomeric states forming, are of vital importance to the ...understanding of nuclear astrophysical processes. Studies of these nuclei, such as
190
Re, can be used to validate and improve theoretical models of such processes. A polarised-beam experiment has been performed using the Munich Q3D magnetic spectrograph in order to investigate the energy-level structure of
190
Re. An excitation-energy spectrum has been produced, allowing for energies to be assigned to observed states. Through comparison between measured and calculated differential cross-sections and vector analysing powers, the process of assigning spin and parity to newly observed states, and confirming the assignments for previously observed states, is underway.
Three-Dimensional Hydrogen Microscopy in Diamond Reichart, P.; Datzmann, G.; Hauptner, A. ...
Science (American Association for the Advancement of Science),
11/2004, Letnik:
306, Številka:
5701
Journal Article
Recenzirano
A microprobe of protons with an energy of 17 million electron volts is used to quantitatively image three-dimensional hydrogen distributions at a lateral resolution better than 1 micrometer with high ...sensitivity. Hydrogen images of a -textured undoped polycrystalline diamond film show that most of the hydrogen is located at grain boundaries. The average amount of hydrogen atoms along the grain boundaries is$(8.1 \pm 1.5) \times 10^{14}$per square centimeter, corresponding to about a third of a monolayer. The hydrogen content within the grain is below the experimental sensitivity of$1.4 \times 10^{16}$atoms per cubic centimeter (0.08 atomic parts per million). The data prove a low hydrogen content within chemical vapor deposition-grown diamond and the importance of hydrogen at grain boundaries, for example, with respect to electronic properties of polycrystalline diamond.
Precision branching-ratio measurements in 18O Pirrie, S.; Wheldon, C.; Kokalova, Tz ...
The European physical journal. A, Hadrons and nuclei,
2021/4, Letnik:
57, Številka:
4
Journal Article
Recenzirano
Odprti dostop
An experiment has been performed utilising the
12
C(
7
Li,
p
)
18
O reaction to populate high-energy states in
18
O. Using the Munich Q3D magnetic spectrograph in conjunction with the Birmingham ...large-angular-coverage DSSD array, branching ratios have been measured for over fifty states in
18
O, investigating the
α
-decay,
n
-decay, 2
n
-decay and
γ
-decay branches. In tandem, Monte-Carlo techniques have been used to identify and separate features.
Excited states in 98Ru were investigated using γ-ray spectroscopy following the β-decay of 98Rh, and via the 100Ru(p,t) reaction. Combining the results from the two experiments, two states were ...revised to have spin-parity of 4+ and subsequently assigned to the 02+ and “γ” bands, respectively. The observed structures in 98Ru are suggested to be deformed and rotational, rather than spherical and vibrational, and fit well into the systematics of these excitations in the Ru isotopes. The 02+ excitation is suggested as a shape coexisting configuration. This observation eliminates some of the last remaining candidates for nearly harmonic vibrational nuclei in the Z≈50 region. Beyond-mean-field calculations are presented that support shape coexistence throughout the Ru isotopes with N=52–62, and suggest a smooth evolution of the shapes.
Mass measurement of Re-190 Griffiths, M R; Wheldon, C; Kokalova, Tz ...
Journal of physics. G, Nuclear and particle physics,
08/2020, Letnik:
47, Številka:
8
Journal Article
Recenzirano
Odprti dostop
In this paper, a measurement of the atomic mass and mass excess of Re75190 are presented. This isotope and Ir77192 were produced at the Maier-Leibnitz Laboratory (MLL) in Munich in the 192Os(d, ...α)190Re and 194Pt(d, α)192Ir reactions. The Q3D magnetic spectrograph was used to measure the momenta of the α-particle ejectiles in order to reconstruct states in both 190Re and 192Ir. A mass calibration was performed using known energy levels in 192Ir. These measurements were used to obtain a new value of the mass excess of 190Re, −35583 ± 5 keV. The previously known literature value is −35640 ± 70 keV.
Abstract
Globular clusters contain multiple stellar populations, with some previous generation of stars polluting the current stars with heavier elements. Understanding the history of globular ...clusters is helpful in understanding how galaxies merged and evolved and therefore constraining the site or sites of this historic pollution is a priority. The acceptable temperature and density conditions of these polluting sites depend on critical reaction rates. In this paper, three experimental studies helping to constrain astrophysically important reaction rates are briefly discussed.
As part of a systematic study of the nuclear structure of the Ru isotopes, 98Ru was investigated via the β-decay of 98Rh at iThemba LABS, and the 100Ru(p, t) reaction at the Maier-Leibnitz ...Laboratory. The combined data results in significant revision of the previous spin assignments and clarification of the nature of levels in 98Ru, as well as providing insights into the evolution of the structures across the Ru isotopic chain.
We used a high-resolution magnetic spectrograph to study neutron pair-correlated 0+ states in 136Ba, produced via the Ba138(p,t) reaction. In conjunction with state-of-the-art shell model ...calculations, these data benchmark part of the dominant Gamow-Teller component of the nuclear matrix element (NME) for 136Xe neutrinoless double beta (0νββ) decay. We demonstrate for the first time an evaluation of part of a 0νββ decay NME by use of an experimental observable, presenting a new avenue of approach for more accurate calculations of 0νββ decay matrix elements.
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