skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Position reconstruction in fission fragment detection using the low pressure MWPC technique for the JLab experiment E02-017

Abstract

When a lambda hyperon was embedded in a nucleus, it can form a hypernucleus. The lifetime and its mass dependence of stable hypernuclei provide information about the weak decay of lambda hyperon inside nuclear medium. This work will introduce the Jefferson Lab experiment (E02-017) which aims to study the lifetime of the heavy hypernuclei using a specially developed fission fragment detection technique, a multi-wire proportional chamber operated under low gas pressure (LPMWPC). Presented here are the method and performance of the reconstruction of fission position on the target foil, the separation of target materials at different regions and the comparison and verification with the Mote Carlo simulation.

Authors:
 [1];  [2];  [3];  [4];  [4];  [4]
  1. Lanzhou U.
  2. JLAB
  3. Yerevan
  4. Lanzhou
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1149583
Report Number(s):
JLAB-PHY-13-1792; DOE/OR/23177-2790; arXiv:1309.7422
DOE Contract Number:
AC05-06OR23177
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chin.Phys. C; Journal Volume: 38; Journal Issue: 07
Country of Publication:
United States
Language:
English

Citation Formats

Xi-Yu, Qiu, Tang, Liguang, Margaryan, Amur T., Jin-Zhang, Xu, Bi-Tao, Hu, and Xi-Meng, Chen. Position reconstruction in fission fragment detection using the low pressure MWPC technique for the JLab experiment E02-017. United States: N. p., 2014. Web. doi:10.1088/1674-1137/38/7/074003.
Xi-Yu, Qiu, Tang, Liguang, Margaryan, Amur T., Jin-Zhang, Xu, Bi-Tao, Hu, & Xi-Meng, Chen. Position reconstruction in fission fragment detection using the low pressure MWPC technique for the JLab experiment E02-017. United States. doi:10.1088/1674-1137/38/7/074003.
Xi-Yu, Qiu, Tang, Liguang, Margaryan, Amur T., Jin-Zhang, Xu, Bi-Tao, Hu, and Xi-Meng, Chen. Tue . "Position reconstruction in fission fragment detection using the low pressure MWPC technique for the JLab experiment E02-017". United States. doi:10.1088/1674-1137/38/7/074003. https://www.osti.gov/servlets/purl/1149583.
@article{osti_1149583,
title = {Position reconstruction in fission fragment detection using the low pressure MWPC technique for the JLab experiment E02-017},
author = {Xi-Yu, Qiu and Tang, Liguang and Margaryan, Amur T. and Jin-Zhang, Xu and Bi-Tao, Hu and Xi-Meng, Chen},
abstractNote = {When a lambda hyperon was embedded in a nucleus, it can form a hypernucleus. The lifetime and its mass dependence of stable hypernuclei provide information about the weak decay of lambda hyperon inside nuclear medium. This work will introduce the Jefferson Lab experiment (E02-017) which aims to study the lifetime of the heavy hypernuclei using a specially developed fission fragment detection technique, a multi-wire proportional chamber operated under low gas pressure (LPMWPC). Presented here are the method and performance of the reconstruction of fission position on the target foil, the separation of target materials at different regions and the comparison and verification with the Mote Carlo simulation.},
doi = {10.1088/1674-1137/38/7/074003},
journal = {Chin.Phys. C},
number = 07,
volume = 38,
place = {United States},
year = {Tue Jul 01 00:00:00 EDT 2014},
month = {Tue Jul 01 00:00:00 EDT 2014}
}
  • A time-zero fission fragment (FF) detector, based on the technique of low-pressure multiwire proportional chambers (LPMWPC), has been designed and constructed for the heavy hypernuclear lifetime experiment (E95-002) at Thomas Jefferson National Accelerator Facility. Its characteristics and the method of time-zero reconstruction were investigated using fission fragments from a 252Cf spontaneous fission source. The influence of the ionization energy loss was also studied. It is shown that Heptane, Hexane, and Isobutane gases at a pressure of 1z2Torr are all suitable for such a FF detector. As desired by experiment, a timing resolution of about 200ps (FWHM) for a chamber sizemore » of 21z21cm2 was achieved.« less
  • Purpose: Efficient optimization of CT protocols demands a quantitative approach to predicting human observer performance on specific tasks at various scan and reconstruction settings. The goal of this work was to investigate how well a channelized Hotelling observer (CHO) can predict human observer performance on 2-alternative forced choice (2AFC) lesion-detection tasks at various dose levels and two different reconstruction algorithms: a filtered-backprojection (FBP) and an iterative reconstruction (IR) method. Methods: A 35 Multiplication-Sign 26 cm{sup 2} torso-shaped phantom filled with water was used to simulate an average-sized patient. Three rods with different diameters (small: 3 mm; medium: 5 mm; large:more » 9 mm) were placed in the center region of the phantom to simulate small, medium, and large lesions. The contrast relative to background was -15 HU at 120 kV. The phantom was scanned 100 times using automatic exposure control each at 60, 120, 240, 360, and 480 quality reference mAs on a 128-slice scanner. After removing the three rods, the water phantom was again scanned 100 times to provide signal-absent background images at the exact same locations. By extracting regions of interest around the three rods and on the signal-absent images, the authors generated 21 2AFC studies. Each 2AFC study had 100 trials, with each trial consisting of a signal-present image and a signal-absent image side-by-side in randomized order. In total, 2100 trials were presented to both the model and human observers. Four medical physicists acted as human observers. For the model observer, the authors used a CHO with Gabor channels, which involves six channel passbands, five orientations, and two phases, leading to a total of 60 channels. The performance predicted by the CHO was compared with that obtained by four medical physicists at each 2AFC study. Results: The human and model observers were highly correlated at each dose level for each lesion size for both FBP and IR. The Pearson's product-moment correlation coefficients were 0.986 [95% confidence interval (CI): 0.958-0.996] for FBP and 0.985 (95% CI: 0.863-0.998) for IR. Bland-Altman plots showed excellent agreement for all dose levels and lesions sizes with a mean absolute difference of 1.0%{+-} 1.1% for FBP and 2.1%{+-} 3.3% for IR. Conclusions: Human observer performance on a 2AFC lesion detection task in CT with a uniform background can be accurately predicted by a CHO model observer at different radiation dose levels and for both FBP and IR methods.« less
  • The purpose of this study is to investigate the effect of initial surface reconstruction on the nitridation process of Al{sub 2}O{sub 3} (0001). This was done by exposing differently reconstructed sapphire substrates at different temperatures to low pressure ammonia (NH{sub 3}). Structural and chemical analysis were carried out using low-electron energy diffraction and x-ray photoelectron spectroscopy. The experiments revealed that using low pressure ammonia (P{sub NH{sub 3}}<1x10{sup -5} Torr), no nitridation takes place on (1x1) unreconstructed surfaces. However, when the unreconstructed surface starts to change to a ({radical}(31)x{radical}(31))R{+-}9 deg. reconstructed surface, with increasing substrate temperature, the nitridation becomes successful. Whenmore » using the initially reconstructed surface, the nitridation is successful even from the lowest temperature used. These results suggest that the initial surface reconstruction has a major effect on the nitridation process. This kinetic behavior has not been reported before, with most nitridation studies mainly focusing on the effect of surface temperature on the resulting surface morphology, rather than the actual kinetics of the process itself.« less