Measuring Pion Beta Decay with High-energy Pion Beams PDF Download
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Category :
Languages : en
Pages : 14
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Book Description
Improved measurements of the pion beta decay rate are possible with an intense high-energy pion beam. The rate for the decay [pi][sup +] [yields] [pi][sup 0]e[sup +]v[epsilon] is predicted by the Standard Model (SM) to be R([pi][sup +] [yields] [pi][sup 0]e[sup +]v[epsilon]) = 0.3999[plus minus]0.0005 s[sup [minus]1]. The best experimental number, obtained using in-flight decays, is R([pi][sup +] [yields] [pi][sup 0]e[sup +]v[epsilon]) = 0.394 [plus minus] 0.015 s[sup [minus]1]. A precise measurement would test the SM by testing the unitarity of the Cabibbo-Kobayashi-Maskawa matrix for which one analysis of the nuclear beta decay data has shown a 0.4% discrepancy. Several nuclear correction factors, needed for nuclear decay, are not present for pion beta decay, so that an experiment at the 0.2% level would be a significant one. Detailed study of possible designs will be needed, as well as extensive testing of components. The reduction of systematic errors to the 0.1% level can only be done over a period of years with a highly stable apparatus and beam. At a minimum, three years of occupancy of a beam line, with 800 hours per year, would be required.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 14
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Book Description
Improved measurements of the pion beta decay rate are possible with an intense high-energy pion beam. The rate for the decay [pi][sup +] [yields] [pi][sup 0]e[sup +]v[epsilon] is predicted by the Standard Model (SM) to be R([pi][sup +] [yields] [pi][sup 0]e[sup +]v[epsilon]) = 0.3999[plus minus]0.0005 s[sup [minus]1]. The best experimental number, obtained using in-flight decays, is R([pi][sup +] [yields] [pi][sup 0]e[sup +]v[epsilon]) = 0.394 [plus minus] 0.015 s[sup [minus]1]. A precise measurement would test the SM by testing the unitarity of the Cabibbo-Kobayashi-Maskawa matrix for which one analysis of the nuclear beta decay data has shown a 0.4% discrepancy. Several nuclear correction factors, needed for nuclear decay, are not present for pion beta decay, so that an experiment at the 0.2% level would be a significant one. Detailed study of possible designs will be needed, as well as extensive testing of components. The reduction of systematic errors to the 0.1% level can only be done over a period of years with a highly stable apparatus and beam. At a minimum, three years of occupancy of a beam line, with 800 hours per year, would be required.
Author: John B Mcclelland
Publisher: World Scientific
ISBN: 9814553506
Category :
Languages : en
Pages : 182
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Book Description
This workshop gives an overview of the physics opportunities that would be created by high-quality, intense pion beams with energies up to about 1 GeV. Topics explored include hypernuclear structure studies using the (π,K) reaction, hyperon-nucleon scattering including polarization, high-energy pion-nucleus reactions such as absorption and double charge exchange, baryon-resonance investigations, and decays of the π and h mesons. The present status of high-energy pion beamlines and instrumentation as well as new directions in the field were also discussed.
Author: John B. McClelland
Publisher:
ISBN: 9789814536172
Category : SCIENCE
Languages : en
Pages : 169
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Book Description
![Branching Ratio for Pion-beta Decay: [pi]+ --> [pi]0 + [epsilon]+ + [gamma] PDF](https://books.google.com/books/content/images/frontcover/g2eZVNhHjr8C?fife=w80-h100)
Author: Robert Bruce Bacastow
Publisher:
ISBN:
Category :
Languages : en
Pages : 62
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Author: Kétévi Adiklè Assamagan
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ISBN:
Category :
Languages : en
Pages : 500
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Author: David F. Bartlett
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ISBN:
Category : Beta rays
Languages : en
Pages : 116
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The conserved vector current theory predicts that the branching ratio for the decay of a charged pion into a neutral pion is (1.05=0.02)x10 to the -8th power, if the coupling constant is derived from muon decay, or (1.00=0.02)x10 to the -8th power, if the coupling constant is derived from nuclear beta decay. Using spark chambers to distinguish the nearly anticollinear gamma rays from pi(+) beta decay from a background of other gamma rays, we have found 36 events and have measured the branching ratio to be (0.97=0.20)x10 to the -8th power, in agreement with the theoretical prediction and previous measurements. The method of background subtraction (approximately 10%) depends only on knowing that the background is isotropic for gamma rays having opening angles between 160 degrees and 180 degrees. (Author).
Author: Alan Strelzoff
Publisher:
ISBN:
Category : Branching ratios (Nuclear physics)
Languages : en
Pages : 66
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The ratio of the pion decay rates for the processes, pi yields e + nu and pi yields mu + nu was measured. A large NaI (tl) crystal was used to separate the high energy pion decay electrons from the continuous spectrum of the pi-mu-e chain. Counting decay electrons immediately following a pion stop, the ratio by a direct comparison of pi-e and pi-mu-e electrons was determined. From an observed 10,891 pi-e electrons a precision of 1.8% was attained in the guantity (pion lifetime x branching ratio). Considering the present uncertainty in the pion lifetime the branching ratio, (1.247 = 0.028) x 10 to the -4 power is obtained. This is in good agreement with the theoretical value, 1.233 x 10 to the -4 power, required by the V-A theory when radiative corrections are included. (Author).
Author: Richard Melvin Marshall
Publisher:
ISBN:
Category : Pions
Languages : en
Pages : 152
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Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 574
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Author: Hartmut Machner
Publisher: World Scientific
ISBN: 9814549169
Category :
Languages : en
Pages : 618
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Book Description
The investigation of hadronic and nuclear probes with protons and electrons in the energy range of a few GeV is of great importance for the understanding of the properties of nucleons and mesons as well as of their interaction. Experimental results from studies with these beams provide the basis for the development and the tests of theoretical approaches in the energy regime of non-perturbative QCD. They can also clarify the effect of the nuclear medium on elementary reactions. The conference has reviewed the present status of this field of research. The topics have beenThe conference topics comprised investigations near energy thresholds in the tradition of the conferences on Particle Production near Threshold in Nashville, IN, USA, 1990, and Uppsala, Sweden, 1992.
