Measurement of the relative partial decay rates for K+ -> pi+pi+pi-
Fletcher, Charles Roberts
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https://hdl.handle.net/2142/25710
Description
Title
Measurement of the relative partial decay rates for K+ -> pi+pi+pi-
Author(s)
Fletcher, Charles Roberts
Issue Date
1967
Doctoral Committee Chair(s)
Wattenberg, A.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
relative partial decay
spark chamber experiment
zero gradient synchrotron
kaons
Language
en
Abstract
A spark chamber experiment was performed at the Argonne
National Laboratory Zero Gradient Synchrotron to measure the
relative partial decay rates of positive and negative kaons
decaying in the tau mode, K+ -> pi+pi+pi-. The ratio measured was
If [equation] differs from unity» there is a CP violation in
the weak process K+ -> (3pi)+/- due to the presence of parity
conserving strangeness changing~6I ~ 5/2 transitions. Also
strong final state pion interactions must be present.
The experimental number measured was
[equation]
where ~ + was the number of tau decays observed and K+ was the
number of kaons from which these tau decays occurred. The tau
decays were observed by photographing the three pions in spark
chambers. The kaons in a beam derived from the external proton
beam were identified by a threshold and a differential gas
Cerenkov counter.
The film taken was scanned twice for taus. The identifying
feature of a tau was three particles from a common vertex with
no particle making an angle of greater than 100 with the direction
of the decaying kaon. The two scans were checked frame by frame
for conflicts in interpretations.
These conflicts were resolved by scanners when feasible
and by physicists.
The value of [equation] observed was based on this
reconciliation of the two scanso
The sources of biases and the corrections to the relative
rates, if any are discussed. The two corrections made to [equation]
were due to the difference in K+ and K- transmissions through
the beam defining counters and to accidentals. The corrections
were +.0014 and -.0014, respectively
The corrected value for the relative tau decay rates was
[equation]
The result is consistent with four interpretations.
1) There is no CP violation in K+ -> (3pi)+/- as seen in the
relative tar: rates within the experimental error of 0.9%.
2) There are no final state pion interactions
3) There is a negligible I=3 contribution to the tau
matrix element,
4) There are weak final state pion interactions and
a small I=3 amplitude.
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