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Measurement of the K{sup 0}{sub S} - K{sup 0}{sub L} mass difference by the time dependence of strangeness

Description: The magnitude of the K{sup 0}{sub S} - K{sup 0}{sub L} mass difference has been measured by monitoring the time dependence of the strangeness of neutral K's produced in hydrogen and deuterium in the LRL 25 '' hydrogen bubble chamber. The particles originate as K-bar{sup 0} in K{sup -} change-exchange scatters at .85 to 1.15 Bev/c; the signature for an S = -1 reaction is the production of a hyperon. Seventy- seven events were found, obtaining {Delta}{omega} = 0.50 =- 0.15, measured in units of inverse K{sup 0}{sub S} lifetime. This and two other recent measurements using the same method are consistent with one another and with measurements of {Delta}{omega} by other means. A combined ''world average'' of nine reasonably consistent measurements gives {Delta}{omega} = 0.60 +- 0.06.
Date: April 1, 1966
Creator: Camerini, U.; Cline, D.; English, J. B.; Fischbein, W.; Fry, W. F.; Gaidos, J. A. et al.
Partner: UNT Libraries Government Documents Department

Optimizing Pinhole and Parallel Hole Collimation for Scintimammography with Compact Pixellated Detectors

Description: The relative advantages of pinhole and parallel hole collimators for scintimammography with compact, pixellated gamma detectors were investigated using analytic models of resolution and sensitivity. Collimator design was studied as follows. A desired object resolution was specified for a pixellated detector with a given crystal size and intrinsic spatial resolution and for a given object-to-collimator distance. Using analytic formulas, pinhole and parallel hole collimator parameters were calculated that satisfy this object resolution with optimal geometric sensitivity. Analyses were performed for 15 cm x 20 cm field of view detectors with crystal elements 1.0, 2.0 and 3.0 mm on a side and 140 keV incident photons. The sensitivity for a given object resolution was greater for pinhole collimation at smaller distances, as expected. The object distance at which the pinhole and parallel hole sensitivity curves cross each other is important. The crossover distances increased with larger crystal size for a constant object resolution and increased as the desired object resolution decreases for a constant crystal size. For example, for 4 mm object resolution these distances were 5.5 cm, 6.5 cm and 8 cm for the 1 mm, 2 mm and 3 mm crystal detectors, respectively. The results suggest a strategy of parallel hole collimation for whole breast imaging and pinhole collimation for imaging focal uptake. This could be accomplished with a dual detector system with a different collimator type on each head or a single head system equipped with two collimators and a rapid switching mechanism. Multipinhole collimators have the potential to increase sensitivity yet maintain high image resolution. An experimental SPECT phantom study with a four-pinhole collimator was acquired with a pixellated detector. The iterative maximum-likelihood expectation- maximization (MLEM) reconstruction of a hot sphere in a warm cylinder showed the potential of multipinhole collimation to improve sensitivity for tomographic pinhole ...
Date: November 1, 2002
Creator: Smith, Mark F.; Kieper, Douglas A.; Majewski, Stan; Weisenberger, Andrew G. & Welch, Benjamin
Partner: UNT Libraries Government Documents Department

Experimental And Theoretical High Energy Physics Research At UCLA

Description: This is the final report of the UCLA High Energy Physics DOE Grant No. DE-FG02- 91ER40662. This report covers the last grant project period, namely the three years beginning January 15, 2010, plus extensions through April 30, 2013. The report describes the broad range of our experimental research spanning direct dark matter detection searches using both liquid xenon (XENON) and liquid argon (DARKSIDE); present (ICARUS) and R&D for future (LBNE) neutrino physics; ultra-high-energy neutrino and cosmic ray detection (ANITA); and the highest-energy accelerator-based physics with the CMS experiment and CERN’s Large Hadron Collider. For our theory group, the report describes frontier activities including particle astrophysics and cosmology; neutrino physics; LHC interaction cross section calculations now feasible due to breakthroughs in theoretical techniques; and advances in the formal theory of supergravity.
Date: July 22, 2013
Creator: Cousins, Robert D.
Partner: UNT Libraries Government Documents Department