New high precision study on the decay width of the Hoyle state in C-12

Precise estimation of the rare direct 3α decay of the Hoyle state of 12C has been made to unveil its unusual α-cluster configurations ranging from linear 3α chain structure to diffuse Bose gas as well as Bose Einstein condensate. The present new high precision, nearly zero background experimental study with Hoyle events has converged on the upper limit for direct decay at ∼0.019% with 95% confidence limit, which is more than a factor of 2 lower than the limit obtained in the previous studies.Two of the authors (S.B. and A.R.) acknowledge the financial support received as Raja Ramanna Fellowship from the Department of Atomic Energy, Government of India

A dosemetric and radiobiological impact of VMAT and 3DCRT on lumbosacral plexuses, an underestimated organ at risk in cervical cancer patients

Background: The purpose of this study was to evaluate dosimetric and radiobiological difference between volumetric modulated arc therapy (VMAT) and 3-dimensional conformal radiotherapy (3DCRT) in organ at risk (OAR) lumbosacral plexus (LSP) in cervical cancer patients. Materials and methods: 30 patients of cervical cancer who were treated using 3DCRT or VMAT along with chemotherapy followed by brachytherapy were enrolled. LSP was delineated retrospectively. Dosimetric and radiobiological difference was evaluated. Patients were followed for radiation induced lumbosacral plexopathy (RILSP). Results: Median follow-up was 12 months (3–16 months). 53.3% of patients were treated by 3DCRT and 46.7% by VMAT. The mean (±SD) LSP volume: 119.03 ± 15 cm3. The mean volume percentages (%) of the LSP: V5, V10, V20, V30, V40, V50, V55, and V60 were 100%, 99.8%, 99.2%, 94.3%, 84.03%, 59.7%, 0%, 0%, respectively. All patients received doses to the LSP in excess of 50 Gy, one patient received 55 Gy. A statistically significant difference was observed in the median value of V20, V30, V40, V50, D50, P2, P4, P7, P8, P9, and P10 across two different techniques of radiotherapy — VMAT and 3DCRT. None of the patients presented with RILSP. NTCP value was less in VMAT plans compared to 3DCRT, which is also statistically significant. Conclusion: RILSP is a rare and often refractory complication of pelvic radiotherapy. Advance radiotherapy technique with proper OAR delineation and constraint can prevent the occurrence of RILSP. VMAT has potential benefits for the probability of dose reduction in LSP. Further studies are required focusing on dose distribution in LSP–OAR and radiotherapy modality

Three-dimensional quasi-quantized Hall insulator phase in SrSi2

In insulators, the longitudinal resistivity becomes infinitely large at zero temperature. For classic insulators, the Hall conductivity becomes zero at the same time. However, there are special systems, such as two-dimensional quantum Hall isolators, in which a more complex scenario is observed at high magnetic fields. Here, we report experimental evidence for a quasi-quantized Hall insulator in the quantum limit of the three-dimensional semimetal SrSi2. Our measurements reveal a magnetic field-range, in which the longitudinal resistivity diverges with decreasing temperature, while the Hall conductivity approaches a quasi-quantized value that is given only by the conductance quantum and the Fermi wave vector in the field-direction. The quasi-quantized Hall insulator appears in a magnetic-field induced insulating ground state of three-dimensional materials and is deeply rooted in quantum Hall physics.Comment: 29 pages including SI, 3 main figures and 6 SI figure

Electronic structures of the electron donor-acceptor complexes of fullerenes C₆₀ and C₇₀ with azulene and some of its derivatives employing <i>ab initio</i> and DFT methods

1461-1467Quantum mechanical calculations have been carried out to determine the structural and electronic properties of the electron donor-acceptor complexes of C60 and C70 with azulene and some of its derivative, viz, 1,3-dichloroazulene, 2-hydroxyazulene and 4,6,8-trimetrhyl azulene. The molecules studied are optimized first with semi-empirical molecular orbital theory at the third parametric level, and, then further optimized by Hartree Fock method. The optimized geometries, calculated energies, spatial distribution, HOMO and LUMO energies along with the electrostatic potential maps of the individual molecules and the electron donor-acceptor complexes are obtained by ab initio and density functional theory methods. The results suggest that the LUMO state of these complexes is localized on the fullerene moiety whereas the HOMO state is positioned on the azulenes. The energy difference of localized LUMO levels strongly depend on the functional group attached to the azulene and the structure of the fullerene-azulene molecular complexes