A study of beta-spectra of once-forbidden transitions

94 Pages·6.602 MB·English

by  Price, Henry C

a B fiam o f m m i m n m m
%
1# o&wjjr fr&e## J!F#
H
Smtattte*! to the Wmul&f of the Graduate School in
F&rtlml M lfiltoint of tho &eqpl#M£g|&& for the
Xtogp#*t Bootor of fhiloeophff to the Department of
Indiana IM rerelty* 1961#
t®Sr
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ACEHaMBfflBIEWS
m
fb© author hereby acknowledges the mid and guidance of
W mtmmr terrene* H* Xsimge?# who dirested mod participated
in the research described In this thesis and whose indefati^
gable energy and wealth of idea# amazed this work to oul-»
situation* In addition the author desires to express hie
appreciation for the- helpful sdrtee of Professor ML1 if*
lomopineki;! especially that concerning certain aapeeta of the
theory of befca^decay* He is further indebted to the Oak Ridge
tohoratorlea Isotopes Btwteieaa for providing the radioasttre
materials# to Dr« i^ t© l f# Jtouey for making the coincidence
jse&aurments aM o^oulatiom* to Beatrice hanger and Betty
Price for. performing certain other calculations* and to the
latter for typing this- thesis*
Tm author- is deeply grateful to professor Allan. 0* &*
Httohell.|- not only for. generous use of the laboratory but
Indeed for stimulation of the author*s original interest in
physios as an undergraduate and for friendly emowagement
throughout the last nine years*
fhis work wm assisted by a grant to Br* banger from, the
Frederick 0ardaer Cottrell fund of the. Research Corporation and
by the Joint progrsii of the §HR and ABC*..
ABSffiAS?
of thm m&t critical of the theory of bet&~
dtoay is th# of its predictions for energy aistri-*
bubiema of ferbiMcn bete^brimsitioms to- the appropriate
o^porlmtntal. moafwamauta* A aonewtod effort has boom made
to find toto*totoflbi<m$ yielding unambiguous distributions
not 'oorrospoiidiiig to- the allowed ahapoa by measuring in a
mm&*Qiwmlm msi»Mb apootrtootor the bata^apaotoa of the
forbidden toanatttontt of T^f Sr8®* X^# He3*86#
^ ?»* »#«* * with thin mw?<am* negligible scattering*
ami t able adnntora m& high resolution*. A xmi%xm type of
forbidden spectra la found for the first five while the last
four yield in^lstinpilaMbla from the allowed shape
ap o o tra
in the rogiona meaawM* Interpretation of those spectra
offers evidence for the reliability of mclear shell models*
im the validity of MS. mtmileal rules* and for the dominance
of the tensor md/m ttia l vector typo interactions in those
beta**tramsit £ons which yield uni-quo ona«*ftobtdd*ft shapes*
Sad points found aw (la Jfev)* 1,337 * o,007j 3r09,
1 ,« 3 * 0*005i f®©, 2,180 * 0.007} Cs1&7, 0*51 t 0,01}
SblS4f s*,a91-'S 0,003, X.S9 1 0,01, 0,95 1 0,03 and lower groups;
Au198, 0,956 r 0,005} He186, 1,063 1 0,006} ?3S, 1.(589 ± Q.Olf
P#«?# 0*208® * 0,0005,
oommm
*43X8 of
4 1
t | A b stract 2
444 fable of dombsntt 8
I f 3
I* SAOM OltB* MSSBMKSf Of fllB PROBLEM 7
if# «nBOB«fiOA$, pxsensaiOT xx
A*. Ifltocduotim IX
8* iergsiib M ft feluee IX
0# Fermi FormuXatica 12
l>* Other FomfiUtieiie 13
I# AppMatiia&bleme 17
%
I# tow Appfes&mebieii 17
8* tow Energy Approximation 18
$# High i Approadbiatlon IS
4* Other Apm^oxlmiiom 10
P.* Screening Correction 10
III* fmoa s fii« W ii£ ifimiiOE so
A* Spectral Shapes 20
B# Angular CtaweXetloae 20
X# El eetroiaMasetr iaao Correlation in
BetaHdeeay 20
2* Bete^gamt Angular Correlation 22
8* G«aa^ga«a Oojprelefclon 23
8# Internal Bre»atF ahlung 24
O* Pooltron-oleofcron Capture Ratios 25
I* Decay SttosiC*# Lltetla*** and CMP ItiXejfr 25
m
if* a rE ii« M * WHO0
A* The Speetreasieter 27
Sowee and Backing Prepar at ion 27
8*.
X* Frepareticp of thin Films 27
2*. Source Definition and Conductivity 30
8* preparation #£ the Source Proper 31
0* Detection 32
f* SSSULTS 35
A* Yttrium 91 35
8* Strontium 8f and Yttrium 90 40
0*. Cesium 187 44
I>* Antimony 184 49
S« Rhenium 186 and Geld 198 55
P* Phosphorus 52 and Promethium 147 55
-«* 3 *►
m 4 '■#
f t# Q M H rn x tm a id m m m n m w fo r p tm h h r work as
A* miMfcjr ©f the m m i Models as
B* Information About Spin and Parity
Changes 64
6 * Hvldeme for the feneor or AadeX
fetter-' X$fcbtr«bi» S3
©* InformtitB F r« Forbidiitn^Trmaition
S tra ig h t I£ m IMS n e t t #6
B* F^tlw Smbstantietita ©£ the <MP
Stlttbioa Rule® 68
fix* J&m&LX 70
A# lucloar Shell struotmii ifp?sli®abl«
to Studied 70
B, Bit simtegr at ion Sthemt ^ ft
#*,. pp *» 1 £*ft for frantltitM Studied 78
©* More lta«b studies of FtrMddto
Bttm fraueititut ft
I* Chtadtbry 88
fill* EEFEIMOBa 87
LIST OS' FIOTRES
glass, iSSS.
■% 30 Conventional P**E plot for
taE lit determined independ­
ently by danger and Soapy*
2 $7 GoOTcgtion&X F-E plot for
the Y** beta^opooWttm#
3 39 Forbidden P-K plot for the
ywl bota^epootrum *.
4 41 Conventional P-K plot for
the spectra of 3r®® and
S3pw in secular equilib­
rium with
$ 49 Forbidden M plot for the
spectrum.,
6 43 Fo||idden P-E plot for the
St*®® spectrum Obtained after
correcting for the Y®°
contribution*
7 45 Conventional and forbidden
F--E plots for data obtained
with a scum of 3r®^ from
which the It®® had been
chemically ©acts?acted *
& 40 Conventional arid forbidden
F-& plota for data obtained
from a thick j0>7 ing/emj*)
ehemlcftlly^extracted Y*'
so u rce*
0 47 Conventional and forbidden
P-E plots for the spectrum
of Oe
*
10 50 Momentum distribution of
th e S b l^ hot arrays*
£1
** 0 m
Urn®,
u #1 SonyontiqhaX F**E plot of
the 66*®* be ta** distribution
In the high energy region*
m 5$ Forbidden F**K plot© of the
■sbr2* be t&^ distribution at
high. energy*
54 Conventional and ones*»for«
15
M M fn W*& p lo ts o f tb s
Sbi®4 data*.
14 S6 Conventional P»1 plot for
t&* spsetvm of
m 6 f C onventional F*K p lo t fo r
tbs spectrum of Aul&B*
16 50 C onventional F*K p lo t fo r
tbs spectrum of Pw#
i f $1 C onventional FwK pj
tbs spectrum of
recorded with a bsktromSh
grid counter -*
fa Conventtonal P<*£ plot for
10
the spectrum of Wz¥*®*
with
recorded a tantalum
grid counter*:
frobSbl$r the Most aigmlf leant cheek on b$t.a<*decsy theory
it m m xm m m t and analysis of the energy .distributions resulting
from, forbidden For brevity ti-ie author chooses
to. designate smoh spectre resulting from forbidden transitions
by the tew forbidion^tf^t spectre (or forbidden spectra)
If they are different from- th e.speetw of allowed transitions!
otherwise* by the torn. aIlow«d*fcype spectra* The characteristic
energy distribution for allowed transitions follows from almost
any theory cs^ltlnimg the ea&eeian of two- light particles* For
forbidden trmneititns^., different m rngf distributions may arise
■from each of the fits relatl vl $tieally invariant inter actions
whlb& transform as scalar* polar' vector* tensor* axial vector,*
and pmm^mmAm- respectively* (IK* IF) Far a threats, invariant
theory* the transformation properties of the product of the wav©
functions &S$#©imb#I with the em itted electron and neu trin o*
h e re a fte r c a lle d th e .interaction*. e » * a t moat* be a lin e a r
ee& M na& lm o f th e above fiv e b a sis in te ra c tio n s* (2E) Ferm i (21?)
original if developed the theory In analogy with the polar vector
interaction of e l r a d i a t i o n theory* Orlte&fteld
and Wigner (10 J consider be % a*4i si nt cgr at ion as a simultaneous
creation of* four- particle# (for mmple* a proton# an electron*
and a neutrino in positive energy states and an tmobaerwable
neutron in a. negative state) loading to the anti symmetrical
m 0
3 m- 4 y (scalar' ■«* axial vector * pseudo sc alar)*
/*
A meson tre.#ta#nt# on tim other hand* proceed# in two steps and
sen rake other Xin&w combination® | e « more natural# tt© theory
m m m t 'decide among the various interactions nor can it really
offer absolute ^e'TO^imcc that all five basic .interactions do
hot enter with varying ©oeffioietifc# governed by yet unknown
ami*# in such & fashion that on# interaction* say the tensor*
is dominant in a given b«tm»fcrm&ttIon while other# or a
combination of other# beoew dominant in other transition#* (If)
S w w # the sspsrisgent&l result# for allowed spectra do exclude
wy 11 m m mmblmx^lons involving; both '? and a or both f and A*
|W# M) liofiH## ms&sursMxtft# and proper analysis of b#bi*#poebra
of forbidden transition* shsmld yield ®mm distinction among
the -possible Interactions# at least establishing a trend#, and
perhaps ellmi&a&ittgs certain of the five ’basic interactions and
certain of linear combination# as serious
contenders#.
■Thai# five infceraofcio®# determ ine two a cts o f se le c tio n '
rule# concerning angular, momentum and parity# the Farad and the
O&mow^feXXer (M S) r u lm * {16* ,21* 20) The polar' v ecto r and
the scalar Infractions im wall as the pseudosc&lar Interaction#
sxdfspt fo r o p p o site p a rity ) lead to n early th e mm» Feri&i ru les*
shil# the 6WP rules# which permit a spin change of one gftcs&er
than the Pmmn1 rules in all orders of forbldd#ni*#ssf ar© obeyed
by the- tensor and eaam tlally also by the axial vector and the
S ■# 4 •** F interactions * Information from forbidden spectra helps