ENERGY LEVELS OF LIGHT NUCLEI. VI Introduction The present article is the sixth of a series of ...

340 Pages·2002·15.06 MB·English

Nuclear Physscs 11 (1959) 1--340, (~) North-Holland Pubhshlng Co, Amsterdam
Not to be reproduced by photopxTnt or tmerohlm without written permission from the publisher
ENERGY LEVELS OF LIGHT NUCLEI. VI
F AJZENBERG-SELOVE
Haver/ord College, Hayer/oral, Pennsylvanza r"
and
T LAURITSEN
Cah/orma Inst,tule o/ Technology, Pasadena, CaD/orma
Received 23 December 1958---11 January. 1959
Introduction
The present article is the sixth of a series of compilations )1 summarizing
experimental mformatlon on the energy levels of the nuclei from He 5 to
Ne u. In form and arrangement, It follows the plan of previous versions,
with only slight modifications made necessary by the increasing amount of
information to be presented Each nucleus is represented by a chagram and
a table in which the known energy levels are mdxcated, together with the
nuclear reactions in whlch they are involved. The hstmgs are supported
by a brief text for each reaction, mainly intended as an annotated blbho-
graphy, but abstracting as far as possible the most relevant reformation
A number of nurnencal tables have been included, listing what appear to be
"best" values for the various level parameters. Although the present sum-
mary is intended to be self-sufficient, in the sense that each diagram or
table entry finds a defense somewhere m the cited hterature, considerations
of space have dictated that much important reformation contained m the
earher versions be omitted here For a more detailed dlscusslon of certain
reactions, and for a more complete blbhography, the reader may wash to
refer to the earher summaries .)x A comprehensive exposition of theory and
experiment as applied to the reactions and spectra of light nuclei has been
published by W E Burcham )2 The experimental data on nuclei with
Z from ll to 20 have been summarized by Endt and Braams a).
ARRANGEMENT OF THE MATERIAL
The dmgrams and their accompanying tables contain, in addition to a
representation of the energy levels and their characteristic parameters, an
indication in each case of the experiments m which particular levels have been
? This work has been supported in part by the joint program of the Office of Naval Research
and the U S Atomic Energy Commission, and by the National Sctence Foundatxon
1
2 F AJZENBERG-SELOVE AND T LAURITSEN
studied Such experiments generally fall within one of two categories
those m which the given nuclelde occurs as the intermediate stage in a
reaction, and those in which it represents the final stage In a few Instances,
"pu-kcip"
for example in reactions, the interest may centre on the target
nucleus Where a compound nucleus is formed, the excitation function may
yield rather detmled information about the energy levels of the intermediate
system To illustrate the general nature of this information, particularly as
regards the breadths, relative Intensities of excitation, and preferred modes
of decay of the various levels, the thin-target excitation functions are shown
on the level diagrams, with approximate relative yields plotted horizontally
agmnst bombarding energy in a vertical direction. To permit direct asso-
ciation with the levels, the vertical scale is adjusted to centre-of-mass
energies, with values of bombarding energy indicated in laboratory coordi-
nates. The cross section scales are arbitrary, chfferent for various products,
and in some Instances rather strongly distorted to extnbit weak resonances
All definitely established resonances are indicated by leaders, and where
space permits, with the (laboratory) energy corresponding to the peak
cross section Where no resonances appear in an excitation function, or
where there is reason to believe that the reaction proceeds without formation
of a compound nucleus, a brace within the level diagram indicates what
products are observed
Reactions In which the nuclelde of interest occurs as the residual nucleus
are indicated on the diagrams by the notation X+a--b, where X, a and b
are the target nucleus, bombarding particle, and ejected particle respectively
Horizontal hnes with this notation are located on the drawings at a height
above the origin equal to the reaction Q-value, as calculated from the mass
table The highest bombarding energy at which observations have been
made is shown by a vertical arrow, drawn to scale unless otherwise indicated.
The levels actually observed are listed In the text for each such reaction,
usually in tabular form Conversely, for each level, the master table lists all
the reactions in which the level has been observed
The nature of decay of the various excited states is shown on the diagrams
by arrows, or where excitation functions are plotted, by notations on the
curves Gamma decays are exhibited by vertical arrows For certain nude-
Ides, separate 7-decay diagrams are presented to permit inclusion of detailed
branching ratio information
On each level In the diagram and in the master table corresponchng to a
given nucleus, a value of the excitation energy is quoted This value represents
the weighted mean derived from all relevant experiments It is of course not
always certain that the different experiments refer to the same level, but we
have assumed that they do so wherever the probable errors overlap and
where there appears to be no obvious inconsistency m such an Interpretation
ENERGY LEVELS OF LIGHT NUCLEI VI
Levels, particle groups, or 7-transitions whose existence is uncertmn are
represented by dashed hnes; uncertain numbers are enclosed m parentheses.
In some cases, where a level is partlcularly broad, this fact has been Indicated
by cross hatching. Among the hghter nuclei, where the level spacing is large,
the breadth of the cross hatchmg Indicates the estimated half-w~dth
The discussion of reactions in the text SI dlwded In the same way as on the
diagrams Features of the reactions such as cross sections, excitation func-
tions, and alternate modes of decay, winch relate primarily to the compound
nucleus, will be found discussed under that nucleus, particle-group spectra,
7-transltions, and Q-values are entered uncter the resldual nucleus Angular
distributlon data are entered in one or the other category, depending upon
winch seems the more approprlate to the case m hand.
Since the emphasis m tins summary is on experimental results, no attempt
has been made to treat theoretical papers in any systematic way or to
maintain a complete bibliography of such papers A partml hst of relevant
theoretical papers is given under the heading "Theory" at the beginn,ng of
each section A detailed account of the shell-model interpretation of the
energy levels of light nuclei has been presented by A. M. Lane .)4
SESSAM DNA SEULAV-Q
The mass values used in the present compilation are hsted at the end of the
article. Almost all of these have been taken from the tables of Wapstra )s
For masses not included In these tables -- and In a few instances where
significant changes have occurred -- we have estimated the masses from the
avadable experimental data; details of the estimates will be found in the
text. For each reaction, the Q-value calculated from the masses, designated
,mQ is listed with the reaction heading, as is the binding energy of the
bombarding particle in the compound nucleus, Eb Both quantities are
in MeV Although the mass values generally are ass,gned probable errors of
five to ten keV, the Q-values are often more accurate Some recently
reported Q-values are included m the text, comprehensive hstmgs have been
pubhshed by Van Patter and Whaling )s
SNOITNEVNOC
nihtiW the snoitatlmIl desopmI by eht tnemermqer of brevRy, ew have
derovaedne to avold the esu of rallfmafnu snoltnevnoc dna snoitaiverbba
eW set forth here some of the symbols hcihw ew have used, together with
their .snoltmhed
E Energy nI ,VeM laboratory setanidrooc unless esiwrehto .deificeps
stpircsbuS ,p ,d t, etc, refer to protons, deuterons, tmtons, etc
0 Angle of observation, in laboratory coordinates unless otherwise
specified
4 F ;EVOLES-GREBN~IZJA DNA T ,sL NESTIRU
General the bombarding energy at winch resonance occurs, specific
Eres
the bombarchng energy at winch the resonant part of the phase shaft
of the parhal wave m queshon reaches 90 °
F Observed width of a resonance, m keV, laboratory coordinates unless
otherwise specified.
aE "Characteristic" energy of a level as determined by certain cond~tlons
on the logarithmic denvatlve of the wave function at the nuclear
surface
Statlshcal weight factor times partml width of parhcle x
"Partial" width, after removal of barrxer penetrahon factors, evalu-
7a 2
ated at Ea
X0 2 "Reduced" partml width, x~Y × ~h3/~Rtt2
I Total angular momentum.
Panty
,"1 T z Isobaric spin quantum numbers. 7,- 1(N--Z)
We have made much use of the several collections of experxmental data
which have become avaalable m recent years. Of these, the most Important
in the present connectxon has been the "Nuclear Data Sheets," pubhshed
monthly by the National Academy of Sciences -- National Research
Council )~ We have also derived great benefit and have extracted much
materml from the compilations of "Neutron Cross Sechons," by Hughes and
SchwartzS), and "Charged Parhcle Cross Sechons," by Jarmxe and Seagrave )9
As always, we owe a parhcular debt to our many colleagues who have
cr~taclzed the draft manuscript and who have been kind enough to supply
material m advance of pubhcatlon The actxve help and advxce of C C
Launtsen, W A Fowler, R F Christy and W. Selove sx gratefully acknow-
ledged We are also much indebted to Miss Barbara Zlmmerman and to
Mrs Jan Rasmussen for thmr invaluable assistance m preparing the manu-
script
References
(to Introductaon)
)1 \V F Hornyak and 1" Lamltsen, Reds Mod Phys 20 (1948) 191,
1" Laurltsen, N R -1 Prehrnmary Report No 5 (1949),
ttornyak, Laurltsen. Morr3son and Fowler, Revs Mod Phys 22 (1930) 291,
1 Ajzenberg and 2 Laurltsen, Revs Mod Phys 24 (1952) 321,
.1 Ajzenberg and 1 Laurltsen, Revs Mod Phys 27 (1935) 77
2) \~ L Burcharn. "Nuclear Reactions, Level~, and Spectra of Light Nuclet", Encyclopedm
of Physics 40, Editor Flugge (Springer, 1958)
)3 '1 I~" b~ndt and C 3I 13raams, Revs Mod Phys 29 (1957) 683
)~ \ 13 Lane, Hew Mod Phys, to be pubhshed
)3 & H \Vap~tra, Physaca 21 {1953)367
b) D 13 Van Pattel and W Whahng, Revs Mod t'hys 29 (1957) 757
ENERGY LEVFLS OF LIGHT NUCLEI VI 5
7) McGinms, Anderson, Fuller, Marion, Way and Yamada, "Nuclear Data Sheets", (National
Research Council, Washington D C)
8) D J Hughes and R B Schwartz, "Neutron Cross Sections", Brookhaven National
Laboratory Report BNL 325 (July 1, 1958) (U S Govt Printing Office, Washington, D C )
9) N Jarmm and J D Seagrave, "Charged particle Cross Sections", Los Alamos Scmntlnc
Laboratory Report LA 2014 (Feb 1, 1957)
Atomic Mass Excesses (M--A) in MeV
n 8 36754-0 0014 N 21 21 00 ~.0 0t~ a
N ~ 9 185-4-0 005
14 t 7 5845=t=0 0014 N '~ 7 002~0 003
H a 13 72564-0 0026 N l~ 4 5284-0 005
H a 15 358 4-0 005 N l~ 10 4024-0 012
H ~ 32 2 -4-2 s N l~ 12 93 :_00v~
He ~ 15 817 +0 005 O 41 12 149-'_0 007 a
He* 3 6073=t=0 0024 O '5 7 287±0 005 a
IIe ~ 12 932 4-0 030 O la 0
He 6 19 398 ±0 029 O 71 4 222 kO 005
He 7 31 5 ±2 a O Is 4 521~0 007
O l° 8 9314-0 012
I.i 5 12 988 +0 200 O :° 13 3 4-2 ~
Li* 15 862 ±0 005
L17 16977 ±0006 F la 220 ±1 a
LI ~ 23 310 ±0005 F la 15 63 ±002 ~
LI 9 28 1 ' 1 ~ t ri7 6 989±0 004
l 'is 6 188=k0 OOb
Be 6 20 3 :~ 0 2 a F l* 4 142±0 007
Be 7 17840 ~0005 F 2° 5 904±0 010
Be* 7 309 _k0 005 F ~l 6 193±0 030 s
Be 9 14 010 4-0 00b
Be °~ 15 560 4-0 007 Ne is 10 415 a:0 200
Bc 11 233q :J=0 13 a Ne ~l 7 398=0 00S
Ne °~ - 1 140=_0 O0S
B 8 25 287 4-0 008~ Ne :1 0 465 0 009
B * 15081 ~0006 Ne ~2 --1 533-0011
B l° 15010 =0006 Ne s3 1 043=0 011
13 n 11 914 ~0006 Ne 4~ 1 113 ~ 0 040 a
B *'l 16917 ±0006
31 lj 20 40 4-0 05 ~ Na 2° 14 187~0 200
Na zi 3 987 ±0 033
(o 32 3 4=2 s N,~ ~2 1 307~0 013
C l° 18 79 4-0 09 a Na 2a --2 744~0 010
C li 13 895 10 007 Na 2t --I 3364-0 013
C 21 3 541 ±0 005
C IJ 6 963 ~0 005 Mg s* --6 853--0 014
C ~ 7 157 :v0 003 Mg ~'- --5 8184-0 014
C i~ 14 305 ~0 005 ~ Mg n* -- 8 569==_0 021
Tile masses excesses are taken from A H ~Vap.tra, l'hyswa 21 (1955) 367 except tor those
marked (a) wlnch are derived from d,tta lex mwcd m the pxescnt article and in (A l 55)
H s, He s
6 F AJZENBERG-SELOVE AND ~* LAURITSEN
H 5
(Not illustrated)
The possible existence of a particle-stable H 6 is discussed by 1B( 57b) *
who pomt out that a T = -32 level of HeS--L15 might plausibly be formed by
combination of H 3 or He 3 and a deuteron in the smglet (T = )1 state at an
energy ~ 2 3 MeV higher than the known 61 7--16 8 MeV level If such a
level exists, calculation of Coulomb corrections and n--H 1 mass difference
suggests a mass excess of 32 22 MeV for H ,5 which would be 0 35 MeV
stable against H~+2n Presumably H 5 would then decay by fl-emlsslon
(m 91 MeV) followed by neutron emission 1B( 57b) A search for delayed
neutrons from L17(7, 2p)H 5 with 320-MeV bremsstrahlung yielded no evi-
dence of formation of H 5 (Ta 58c) It is concluded that less than 1% of the
expected yield of LIT(y, 2p)H ~ leads to a particle-stable product (Ta 58c),
see also eC( 58) A reaction yielding H 5 might be H3(t, p)H 5 with Q ~ -8,1
MeV, assuming the mass of H 5 given by 1B( 57b)
He 5
(Fig I, p 7)tt
I H3(d, y)He 5 Qm = 61 629
At Ed = 061 keV, the capture cross section SI less than 0 5 mb This hmlt
is not inconsistent with/'v ~ 11 eV as estimated from the mirror reachon
He3(d, 7)L15 (Sa 55b)
TABLE 5 1
Energy levels of He 6
Ex in He 5 J~ /' Decay Reactions
(MeV) (MeV)
0 |- 0 55± 0 03 n, V, VI, VIII, IX,
X, XI, XII, XIII,
XIV, XVI, XVII
3--6 3---5 n, 0t VIII, XIV
16 69 i+ 0 80 n, d, t, ¢~ II, VIII
~( 20) >I n, d, t, ¢c II
II (a) HZ(d, n)He 4 mQ = 71 586 Eb ---- 61 629
(b) H3(d, 2n)He 3 mQ ---- --2 199
)c( Ha(d, pn)H 3 mQ = --2 226
oQ ---- 71 580+0 025 (Ma 57f)
Excitation curves and angular distributions for reaction (a) from E d
=-: 8 keV to 01 MeV are summarized by (Ja 57, Fo 56a) Addlhonal data
References are collected at the end of the artmle
?t For level scheme of L15, see fig 2, p 13
5_4~
102 He s
7
r~
+ 70
t-
20 ~ 91 620
81 855 +SeH 2 n
H3+b+n
61 629 ~-~
H s+ d )IG -- ~:--:_'_: !215
14 09
T851.5~
!00 Ll%t-a
14163
L~+ d-a
65111 V
+aH pLeH
54~
0839
eH-d%lL s
He 5 - ~ ~,
2 529
a-,)%eB .~ 481
p-d+4eH
29 December 1958
Fig 1 Energy levels of He 6 In these diagrams, energy values are plotted vertically m MeV. based on the
ground state as zero Uncertaan levels or transitions are indicated by dashed hnes, levels which are known to
be particularly broad are cross-hatched Values of total angular momentum jr, panty, and sobanc spin T which
appear to be reasonably well estabhshed axe mdxcated on the levels, less certain assignments are enclosed m
parentheses For reacbons m wl~ch He 5 Is the compound nucleus thin-target excltabon functions are shown
schematically (where know-a), with the yield plotted horizontally and the bombarding energy vertically
Bombaxdmg energies are indicated m laboratory coordinates and plotted to scale m centre-of-mass coordina-
tes Excited states of the restdual nuclei revolved m these reactions have generally not been shown, where tran
stbons to such excited states are known to occur, a brace has been used to suggest reference to another dtagram
For reactions n~ which the present nucleus occurs as a residual product, excitation functions have not
been shown, a vertical arrow with a number indicating some bombarding energy, usually the highest, at
which the reaction has been studied, m used instead
Further reformation on the levels illustrated, including a hstmg of the reactions m which each has been
observed, s2 contained in the master table, entitled "Energy ~ e~e~ of He s''
He 5
8 F AJZENBERG-SELOVE AND T LAURITSEN
are given for Ea = 0 04 to 0 37 MeV by (Ba 570, Ba 57p), for Ed = 1 0 to
58 MeV b 3 (Ga 56) and for Ea--=025 to 70 MeV by (Ba 57h) Below
Ea = 001 keV, the cross section follows the Gamow function, a = (A/E)
exp (--44 40 E-~) (Ja 53d, Ar 54) A strong resonance, a(peak) -- 5 0 b,
appears at Ea = 701 keV A precision measurement (-b 5 %) of the cross
section at Et= 150 MeV gives 200 and 196 mb/sr (cm) at 30 ° and
60 ° (lab), respectively 1A( 58b) There is some question as to whether a
broad maximum exists between 4 and 8 MeV (Ga 56, Ba 57h)
In the region Eo = 01 to 500 keV, the cross section is closely fitted with
the assumption of s-wave formation of a = 3+ state, with the parameters
given in table 5 2 For a given interaction radius, two sets of parameters are
TABI E 5 2
Resonance parameters for HZ(d, n)HO and HO(d p)HO
L r l'l~b j. p,nI (× R I I EA ~d ~ ~,p 0d c'~ 0 n, Ic p Ex
(ke\) (keV) 10-13cm)' (keV) (keV) (keV) (Me\)
I07 a 135 ~ + 5 0 --464 2000 56 1 0 0 018 16 69
7 0 --126 715 17 0 7 001I
+~
430 u ~450 5 0 I -- 391 2930 42 1 4 0 013 16 81
7 0 I 129 780 12 0 7 0 008
¢
I
a HS(d, n)He 3 (Co 52f, Ar 52d, Ku 55~ See also (Ba 570, Ba 57p)
b He~(d, p)HO (Ku 55)
o Umts of 3h212MR 2
obtained, depending upon whether F./Fa is assumed > 1 or < 1 (Ar 52d,
Co 52I) Agreement with the mirror reaction, Hea(d, p)HO, is obtained with
the second choice (Ku 55) The fact that the proton width SI relatively small
suggests that this level arises from excitation of the He 4 core See also 1F( 51),
(Jo 54b), (Jo 55b), (Le 58c), (Ha 55e, theo) and (Da 57a)
The angular distribution of neutrons is lsotroplc at and below resonance,
and shows increasing forward peaking at hlgher energies (Ja )75 Angular
distributions at Ea = 6 MeV are almost identical to those of H3(d, p)HO
(Br 57e) At Ea -= 01 MeV, the distribution is dominated by the stripping
process, with pl = 0 (Bu 511) Again, close correspondence is found with the
marror reaction See also (He 55a, Ba )65 See also (Pa 58b, Le 58c)
At Ea = 21 to 41 MeV, reactions (b) and )c( are observed (Bo 56g,
Br 58b) The He a distributions from (b) show no evidence for a bound
dineutron or for a well-defined virtual state, although some interaction
between the neutrons does appear to occur Absolute differential cross
sections are reported (Br 58b)
For Ea > 3 17 MeV, deuteron breakup (reaction c) is energetically possi-
ble The cross sectlon for this process has been studied for Ea -=-- 3 8 to 6 0
MeV by (He 55d) At Ea = 14 MeV, the number of lo~-energy 4( to 01 MeV)
He 5
ENERGY LEVELS OF LIGHT NUCLEI VI
neutrons is about three times as large as observed in the corresponding
reaction He3(d, pn)He 3 The difference may indicate formation of a T = 0,
22-MeV excited state of He 4 via H3(d, n)He 4. (Bo 56g, Bo 561, Bo 56m,
see, however, Br 58b). See also (Ba 55t), (Co 54l), (Be 55j), (La 55e, theo ),
1B( 56d, theo), (Fo 56a), 1B( 57b), (Po 58, theo)
III HS(d, p)H 4
Assuming the atomic mass excess of H 4 -~ 26 MeV 0f first "7 = 1 state in
He* has Ex ---- 22 MeV), mQ for this reaction would be --4 MeV This
reaction has not been observed (Mc 51a) An attempt has also been made
by (Re 55 0 to observe the fl-decay of H 4 formed m the 300-MeV proton
bombardment of C 21 The results are negative if ½3 ~ (2 to 4)× 10 -3 sec,
a< lpb, if 3½= (4 to 10)×10 -3 sec, a < 10/zb See also (No 57a
B10(L1 ,~ H4)N~).
IV. HS(d, d)H s Eb : 16 629
Dlfferentxal cross sections for Ed --: 0 96 to 3 2 MeV are tabulated by
(St 52e) and for Ea = G1 MeV by 1A( 52b), see also (Br 57e, Ja 57) The
distributions are closely similar to those for HeS(d, d)He 3 See also (Ba 58n)
V. HS(t, n)He 5 0m = 10 371
The ground state of He 5 has been observed at E t ~ 1 48 MeV (Ba 57e)
and 1 9 MeV (Ja 56d). The neutron spectrum contains an excess of medmm-
energy neutrons, attributed to direct 3-body reaction or to a broad excited
state of He .5 An earlier reported peak corresponding to a 2 6-MeV excited
state (Le 51a) is not confirmed (Ba 57e) The aipha~ show a double peaking,
reflecting the influence of the Pt ground state, superposed on a dlstnbutmn
arising from the ½P state and direct 3-body dlsmtegratmn (Ja 58), see He e
VI H3(He ,a p)He 5 mQ = 11 136
Qo---- 11 184-0.07 (AI 53a)
Q0= 11 13+0 07 (Mo 53d)
The spectrum shows a well-defmed proton peak corresponding to the
ground state, superposed on a background attributed to the three-body
breakup (AI 53a, Mo 53d) See also (Go 54c)
VII H~(~, d)He 5 mQ = --7 215
Not observed.
VIII He*(n, n)He 4 Eb ~- --0 957
Total cross sections for En ----- 0 0004 eV to 20 MeV are given in (Hu 55c,
Hu 57, Hu 58), angular distributions of (Ad 52)and (Se 53) are given in
(Hu 56) addltlonal data for En ----- 2 6 to 4 1 MeV are given by (St 57c), for
En =-- 14 MeV by (Sm 54, Sh 55) and at En = 15 7 MeV by 1A( 54c) The
He 5
o1
~ AJZE~B~C-SBLOVE AND T LA.~ITSE~
current experimental and theoretmal situation SI surveyed by (Ho 58a)
The total cross section has a peak of 7 4 b at En = 1.15±0 05 MeV, Ecru
-= 0 95, wlth awldth of ~ I 7 MeV (Ba 51a), Fern -- 1.4q,0 9 MeV (Hu 58)
The thermal cross sectlon is 0 78b (HI 51), 0 71q.0 I b cM( 51d), 0 74q,0 04b
oS( 55a)
Both the total cross sections and the angular distributions are well accoun-
ted for by the phase shifts determined by (Cr 49a, Do 52b) for Hea(p, p)He 4
with a shift in E a of about 1 MeV see also 1C( 55a, theo ) Earlier dlscrepan-
cms m the range 3 to 4 MeV (Hu 52c) appear to have been resolved by
(St 57c) In a polarization measurement, (Le 57b, Le 57d) fred ~(P½) ----
12q.1 ° at En ----- 2 45 MeV, in disagreement with the value ~( = 20 ° derived
from He4(p, p)He ,4 but agreeing with a low cross section point at En ~-- 2 16
MeV reported by (Se 53) The s-wave phase shift decreases monotonically
with increasing energy, and can be accounted for by hard-sphere scattering,
with R -= 2.9× 01 31- cm (Ad 52, Do 52b, see, however, Br 54a, Ho 54g,
Ho 551, Va 56a) The P~ shift shows strong resonance behavlour near 1 MeV,
while the ½P shift changes more slowly, possibly indmatmg a broad ½P level
at several-MeV excitation (Do 52b) At En = 51 7 MeV the angular chstri-
button is best accounted for ~lth 5(D~) = --14 °, ~(D~) = --7 °, the latter
being somewhat less than the hard-sphere value, suggesting a lugher resonan-
ce 1A( 54c) Theory see 51L (For present purposes, the ground state of He s
s~ assumed to correspond to the maximum In the total cross section, Ecru
---- 0 95 MeV)
A resonance SI reported at En -- 22 154-0 31 MeV, F ~ 021 keV, corre-
sponding to the 61 7-MeV level (see Ha(d, n)He )s (Bo 57e) See also (In 57)
Polarization of neutrons scattered m He has been discussed by (Ad 52,
1S 53, Wh 57a, Se 53, Le 55b, Le 56d, Le 57b, Le 57d, Pa 58b) and others
IX (a) He4(d, p)He 5 mQ --- -3 184
(b) He'(d, pn)He 4 mQ --- --2 226
Q for reaction (a) = -3 10±0 05 (Fr 54h)
The proton spectrum observed at Ed = 14 8 MeV, 0 ~ 91 5 °, shows a
prominent peak, of width Pc m = 550±30 keV, and a monotonic continuum
of lower energy protons, attributed to reaction (b) There is no evidence of
structure corresponding to possible sharp excited states of He .5 Cross
sections for the ground state group are =-Dd/ad 25+5 mb/sr at 0cm
= 81 ° and 15q- 4 mb/sr at 0 c m = 24° The dimensionless reduced width
of the ground-state group, analyzed by stripping theory SI 0 ~ = 0 05, more
than a factor of 01 smaller than is Indicated by He4(n, n)He 4 (see xL 5
He4(p, p)He )4 (Wa 56e, Wa 57) For reaction (b), see 61L
X L16(7, p)He 5 mQ = -4 655
The threshold is E 7 = 4 64q,0 08 MeV (Ry 58), see 1L e