Thu·May 11, 2017Thursday·May 11, 2017

1. 01*

   Study of the long-lived excited state in the neutron deficient nuclides ${}^{195,197,199}$Po by precision mass measurement

   N. A. Althubiti🇬🇧 · D. Atanasov🇩🇪 · K. Blaum🇩🇪 · T. E. Cocolios🇬🇧 · T. Day Goodacre🇨🇭 · G. J. Farooq-Smith🇬🇧 · D. V. Fedorov🇷🇺 · V. N. Fedosseev🇨🇭 · S. George🇩🇪 · F. Herfurth🇩🇪 · K. Heyde🇧🇪 · S. Kreim🇨🇭 and 14 other authors

   Direct mass measurements of the low-spin $3/2^{(-)}$ and high-spin $13/2^{(+)}$ states in the neutron-deficient isotopes ${}^{195}$Po, ${}^{197}$Po, and high-spin $13/2^{(+)}$ state in ${}^{199}$Po were performed with the Penning-trap mass spectrometer ISOLTRAP at ISOLDE-CERN. These measurements allow the determination of the excitation energy of the isomeric state arising from the $\nu$i${}_{13/2}$ orbital in ${}^{195,197}$Po. Additionally, the excitation energy of isomeric states of lead, radon, and radium isotopes in this region were obtained from $\alpha$-decay chains. The new excitation energies complete the knowledge of the energy systematics in the region and confirm for the first time that the $13/2^{(+)}$ states remain isomeric, independent of the number of valence neutrons.

   nucl-exPRC(2017)·11 citations
2. 02*

   Data Unfolding with Wiener-SVD Method

   W. Tang🇺🇸 · X. Li🇺🇸 · X. Qian🇺🇸 · H. Wei🇺🇸 · C. Zhang🇺🇸

   Data unfolding is a common analysis technique used in HEP data analysis. Inspired by the deconvolution technique in the digital signal processing, a new unfolding technique based on the SVD technique and the well-known Wiener filter is introduced. The Wiener-SVD unfolding approach achieves the unfolding by maximizing the signal to noise ratios in the effective frequency domain given expectations of signal and noise and is free from regularization parameter. Through a couple examples, the pros and cons of the Wiener-SVD approach as well as the nature of the unfolded results are discussed.

   ↳ physics.data-anhep-exnucl-exJINST(2017)·68 citations
3. 03*

   A novel approach to the bias-variance problem in bump hunting

   Mike Williams🇺🇸

   This study explores various data-driven methods for performing background-model selection, and for assigning uncertainty on the signal-strength estimator that arises due to the choice of background model. The performance of these methods is evaluated in the context of several realistic example problems. Furthermore, a novel strategy is proposed that greatly simplifies the process of performing a bump hunt when little is assumed to be known about the background. This new approach is shown to greatly reduce the potential bias in the signal-strength estimator, without degrading the sensitivity by increasing the variance, and to produce confidence intervals with valid coverage properties.

   ↳ hep-exnucl-exphysics.data-anJINST(2017)·16 citations
4. 04*

   Measurement of basic characteristics and gain uniformity of a triple GEM detector

   Rajendra Nath Patra🇮🇳 · Rama N. Singaraju🇮🇳 · Saikat Biswas🇮🇳 · Zubayer Ahammed🇮🇳 · Tapan K. Nayak🇮🇳 · Yogendra P. Viyogi🇮🇳

   Large area Gas Electron Multiplier (GEM) detectors have been the preferred choice for tracking devices in major nuclear and particle physics experiments. Uniformity over surface of the detector in terms of gain, energy resolution and efficiency is crucial for the optimum performance of these detectors. In the present work, detailed performance study of a 10x10 cm^2 triple GEM detector operated using Ar and CO_2 gas mixtures in proportions of 70:30 and 90:10, has been made by making a voltage scan of the efficiency with 106^Ru-Rh beta-source and cosmic rays. The gain and energy resolution of the detector were studied using the X-ray spectrum of 55^Fe source. The uniformity of the detector has been investigated by dividing the detector in 7x7 zones and measuring the gain and energy resolution at the center of each zone. The variations of the gain and energy resolution have been found to be 8.8% and 6.7%, respectively. These studies are essential to characterise GEM detectors before their final use in the experiments.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2017)·31 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.