•Part I explores the projectile impact response and damage of titanium-based fiber metal laminates (FMLs) using air gun set up.•The damage pattern, energy absorption, and opening of delamination ...between different layers are affected by distributing titanium layers through the thickness.•The ballistic resistance of FMLs is found to be independent of the dispersion of metallic layers within FMLs.•The lateral delamination spread, interlayer opening, and global bending deformation of titanium-based FMLs seem lower than aluminium-based FMLs.
This two-part article examines the distribution of metallic layers through the thickness of fiber metal laminates (FMLs) on their response and damage when subjected to high-velocity projectile impact. Glass fiber/epoxy and Ti-6Al-4V titanium alloy sheets are used to obtain four different layups of FMLs fabricating by the hand layup process and exhibiting the same thickness of the total metal layer. Part I deals with experimental investigations of fully clamped square FMLs normally impacting at the center by hemispherical steel projectile using compressed air gun set up. Different parameters are considered to evaluate the FMLs’ performance, which includes damage degree, first cracking energy, crack length, deformation profile, and damage developed on the surface and inside the laminate. The results indicate that the highest permanent deformation and cracking are exhibited by FML 4/3-0.3, exhibiting separation of composite layers with different orientations by the metallic layer. The other FMLs exhibit lower and approximately similar permanent deformations. However, lower cracking and a relatively higher lateral delamination spread and opening of the interlayer are exhibited by FML 2/1-0.6 in which composite layers are arranged together than FML 4/3-0.3, signifying that the damage spreading laterally can be reduced by dispensing titanium layers. The ballistic resistance is found to be similar for FMLs. The levels of permanent deformation, cracking, and delamination with their opening and spreading are lesser for titanium-based FMLs than aluminium-based FMLs. The ballistic response of FMLs will be evaluated using analytical modeling in an accompanying study (Part II).
The Korea Invisible Mass Search (KIMS) collaboration has developed low-background NaI(Tl) crystals that are suitable for the direct detection of WIMP dark matter. Building on experience accumulated ...during the KIMS-CsI programs, the KIMS-NaI experiment will consist of a 200 kg NaI(Tl) crystal array surrounded by layers of shielding structures and will be operated at the Yangyang underground laboratory. The goal is to provide an unambiguous test of the DAMA/LIBRA annual modulation signature. Measurements of six prototype crystals show progress in the reduction of internal contamination from radioisotopes. Based on our understanding of these measurements, we expect to achieve a background level in the final detector configuration that is less than 1 count/day/keV/kg for recoil energies around 2 keV. The annual modulation sensitivity for the KIMS-NaI experiment shows that an unambiguous 7
σ
test of the DAMA/LIBRA signature would be possible with a 600 kg year exposure with this system.
•Part II deals with the dynamic response of titanium-based FMLs undergoing ballistic impact using analytical modeling.•The leading part of the total energy absorption of FMLs is by bending and ...membrane energy absorption associated with the deformation of FML constituents (68 % - 72 %).•Varying placements of the titanium layers affect the partition of the energy absorption of FMLs.•The predicted ballistic resistance parameters of FMLs are found to be in good agreement with experiments.
This two-part article scrutinizes the influence of metal layer distribution through the thickness of titanium-based fiber metal laminates (FMLs) on their high-velocity projectile impact response and damage. The four different layups of FMLs consist of layers of glass fiber/epoxy and Ti-6Al-4V titanium alloy sheets, exhibiting the thickness of the total metal layer the same. Part I presents the experimental investigations of fully clamped FMLs demonstrating performance parameters, damage mechanisms, and ballistic resistance. Part II concerns the ballistic impact behavior of FMLs using analytical modeling, which is based on test results obtained in an accompanying study. An equivalent mass-spring system is used to obtain the transient deformation, ballistic limit, and absorbed energy of the laminate by various mechanisms. Good agreement is obtained between experimental and analytical ballistic limit velocity. The foremost part of the total energy absorption is by bending and membrane energy absorption (68 % - 72 %), with FML 4/3-0.3 absorbing a higher percentage of aforementioned energies followed by that of both FMLs 3/2 and FML 2/1-0.6. The predicted total energy absorption by several damage mechanisms of FMLs at the ballistic limit displays a reasonable matching with experiments.
Understanding molecular femtosecond dynamics under intense X-ray exposure is critical to progress in biomolecular imaging and matter under extreme conditions. Imaging viruses and proteins at an ...atomic spatial scale and on the time scale of atomic motion requires rigorous, quantitative understanding of dynamical effects of intense X-ray exposure. Here we present an experimental and theoretical study of C60 molecules interacting with intense X-ray pulses from a free-electron laser, revealing the influence of processes not previously reported. Our work illustrates the successful use of classical mechanics to describe all moving particles in C60, an approach that scales well to larger systems, for example, biomolecules. Comparisons of the model with experimental data on C60 ion fragmentation show excellent agreement under a variety of laser conditions. The results indicate that this modelling is applicable for X-ray interactions with any extended system, even at higher X-ray dose rates expected with future light sources.
A
bstract
Limits on the cross section for weakly interacting massive particles (WIMPs) elastic scattering on nuclei in NaI(Tl) detectors at the Yangyang Underground Laboratory are obtained from a ...2967.4 kg·day data exposure. The nuclei recoiling from the scattering process are identified by the pulse shape of the scintillation light signals that they produce. The data are consistent with a no nuclear-recoil hypothesis, and WIMP-mass-dependent 90% confidence-level upper-limits are set on WIMP-nuclei elastic scattering cross sections. These limits partially exclude the DAMA/LIBRA allowed region for WIMP-sodium interactions with the same NaI(Tl) target material. The 90% confidence level upper limit on the WIMP-nucleon spin-independent cross section is 3.26×10
−4
pb for a WIMP mass of 10 GeV/c
2
.
This study aims at evaluating the symptom response, response duration, and toxicity of single dose palliative liver radiotherapy (RT) for symptomatic HCC patients. We reviewed unresectable HCC ...patients treated with palliative RT in our institution. Eligible patients were unsuitable or refractory to trans-arterial chemoembolization (TACE) and stereotactic body radiotherapy (SBRT), with an index symptom of pain or abdominal discomfort. The primary outcome was the percentage of patients with clinical improvement of index symptom at 1 month. Secondary outcomes were response duration, toxicities, alpha-feto protein (AFP) response, and radiological response. Fifty-two patients were included in the study. The index symptom was pain in 34 patients (65.4%), and abdominal discomfort (34.6%) in 18 patients. At 1 month, 51.9% of patients had improvement of symptoms. Median time to symptom progression was 89 days (range: 12-392 days). Treatment was well tolerated with only 2 patients (3.8%) developing grade 3 GI toxicities. AFP response, radiological response rate, and disease control rate at 3 months were 48.6%, 15.1%, and 54.5% respectively. Half of the patients had improvement of index symptoms after receiving palliative liver RT with median response duration of 3 months. The treatment was well tolerated with minimal toxicities.
The annual modulation signal observed by the DAMA experiment is a long-standing question in the community of dark matter direct detection. This necessitates an independent verification of its ...existence using the same detection technique. The COSINE-100 experiment has been operating with 106 kg of low-background NaI(Tl) detectors providing interesting checks on the DAMA signal. However, due to higher backgrounds in the NaI(Tl) crystals used in COSINE-100 relative to those used for DAMA, it was difficult to reach final conclusions. Since the start of COSINE-100 data taking in 2016, we also have initiated a program to develop ultra-pure NaI(Tl) crystals for COSINE-200, the next phase of the experiment. The program includes efforts of raw powder purification, ultra-pure NaI(Tl) crystal growth, and detector assembly techniques. After extensive research and development of NaI(Tl) crystal growth, we have successfully grown a few small-size (0.61–0.78 kg) thallium-doped crystals with high radio-purity. A high light yield has been achieved by improvements of our detector assembly technique. Here we report the ultra-pure NaI(Tl) detector developments at the Institute for Basic Science, Korea. The technique developed here will be applied to the production of NaI(Tl) detectors for the COSINE-200 experiment.
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