Conzett, H. E.

Shield, E.

Slobodrian, R. J.

Yamabe, S.

H.E. Conzett

R.J. Slobodrian

S. Yamabe

E. Shield

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ELASTIC ALPHA-ALPHA SCATTERING NEAR 40 Mev

Conzett, H.E.

Slobodrian, R.J.

eScholarship - University of California

ELASTIC ALPHA-ALPHA SCATTERING NEAR 40 MeV

UNT Digital Library

U:CRL-11382 ;3 ~/1/F-s&.z -~ UNIVERSITY OF CALIFORNIA Lawrence Radiation Laboratory Berkeley, California AEC Contract No. W -7405-eng-48 Foes i mile Price $--r,c....Z..,.r<-...</<:.._....,!/>:.._~ _ Microfilm Price $ c> /1J 1 a_ v Available from the Office of Technical Services Department of Commerce Washington 25, D. C. M· STER ELASTIC ALPHA-ALPHA SCATTERING NEAR 40 MeV H. E. Conzett, R. J. Slobodrian, S. 'Yamabe, and E. Shield ....... April 21, 1964 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. i. I I I THIS PAGE WAS INTENTIONALLY LEFT BLANK I. I: I / .. .)' ' .I ... ~ ·uu? .. L-·\\sn 3a -iii-ELASTIC ALPHA•ALPHA SCATTERING NEAR 4o MeV H. lj:. Conzett, R. J. Slobodrian, 8~ Ywna.be, and E. Shield · Univ. of Calif., :tawrence Radiation Ie."boratory, Berkeley, Calif., U.S.A. ABSTRACT In order to investigate suggested rapid energy variation of the a 1 d and g-'Wave phase shi:f'ta near 40 MeV,; we ·hav.e_ measured differential. ·· .......... . . . cross sections for alpha-alpha scattering over center-of-mnso angles from 16 to 100 degrees at nine energies between "57 and 43 MeV. Analysis of these data is ~derway and is directed to~ard determining ~hether reso-nances corresponding to states in ~ 8 or threshold effects· :of opening reaction che.nnel:s are responsible for the' indicated behaVior of the phase · shi:rts. · ' '. -----------~---3a -1- UCRL-11382 · ELAST!C .ALYti.A-ALPHA .SCATTERII:lG EEAA 4o MeV ... . . . . . H·. E.- Conzett, R. J. SlobOdrian, S. Ywnt.'t'be end E• Shield. Univ. ot Calif'.,, Lavrencc Radiation Le.bora.tory1 .Berkeley1 Calif., U.S.A. A recent phase shift ~sis (1] -O~ th~ alpba•al.pba. elastic scat• tering data avaUable betlleen 23 and 47 MeV [2;3 l bas indieated ·a rapid ener£!3 variation of the e1 d and e•'\ia.ve pi1ase ahU'ts ~ ·4o MeV. 1'bis behavior contrasts markedly ~1th tneir ot~~ise rather .smooth dependence I on energy f'rom 23 t() 120 MeV [1~21 4]; and Irl.ght be interpreted ao evidGnce f~ x-osone.nces correeponding to 0+1 2+1 tmd 4+ states of Be8 (with ap .... preaiable reduced widths for decaying to two &~be particle a). RO'tllever 1 . . ' 4 4 . since the threshold energy for the first ·reaction channel (He +He.,. L17+ l>) is 34" 7 ~ieV and several other reaction ci~els open near 4o MeV$ the poa-· sibility exists that threshold effects may be responsible for the suggested closely apa<~ed 1;n enE:"l"gy are needed before this queation -~an be resolved. The variable-~nergy feature of the Berkeley 88-inch cyclotron has simplified considerably just auch on experimental investigation~ 'l'hus1 ve bs.ve meaaured di:f'ferential ~oss seetic;>ns for al:pha•al:phs scattering I over center-of..:m~s angles :f'roO!li l6 to 100 dec;r:-eea at nin~ energieS bet"'Yeen 37 and 43 MeV. T'ne energy resolutio~ vas bettor than 200 keV~ and the angular resolution -was approximately_ 0.25 degree. Angular distrib~iona determined. at 391 4o, and 4lll~V nre show in Fig .. 11 vhcre they d.emorwtre.te the very r.a:pid variation 'I;Iith. energy previously seen in lese detail. [:5]. . . The insert in Fig. 1 sho'l:lS the excitation curve for alpba•al.pba_ scattering at tbe center-of-mass angle 0 = 56~ (elab = 28°), ~hich is near the position of the :first zero of the Legendre polynalliaJ. P0 (coae).. This is cle.&r evi-~ e dence for rapid changes in the 8 s:nd/or S•'WO.ve phase Bhi~S in the energy interval ~how. ·.-2. UCRL-11382 A phase ehi.:ft analysis o:f these data is presently underway; the re.sul.tB of llhich vill be reported in the near future .• I ! .. We are deeply indebted to A• T. :Berztiss for communicatins tO ! . . us the results of hie pl:).aae•shift analyses prior to publication and1 thus 1 cal.ling to our att~tion the rather unexf>eoted ~havior of the phase shifts near 40 MeV. ,We ere also gratef'ul to P. Da.rriulat, H. D. Ho.lm.gren, G. Igo1 and H. G. Pugh for discusaions concerning their results before pUblication. ! • UCRL-11382 ~ . . 0 ~ . Permanent a.Mreas: ibyGicG Depe:rtm1ent1 OE3aktl Un1verrdty, sulza; Qal'Wl• (ll ~A. tt •. ~~tias, .tm.t.va-td.ty of Melbotu.~ (private ~cation). [2) Ea = 2' to ;S l<WV: D. J •. BrfX!in1 W. E~ ~ll"cr~; D. Ew:ns1 1:. M. G!boon, 3. s. c. ~~ef~e,. ]). J. Pro\fac$ :t. Rotblatj) rout Jf; u. l$nyde:r, ~. nor. Boc. (wndo.n) &.~.a~ 14; (1959). £:>] 101 ~ '7 to 47 MeVi U., E. Con$ett1 G. 1@'..0; H. C. Shaw1 and R. J. Siol»d:'1an;: P~G" R\W•· l..lj; 1075 (1960)• · . •' . . RQ.Q.iation ~toru..toey, ~lwl.ey (private «>ru:nunication). ~ , _-. I_ e UCRL-11382 ·' FIGURE CAPrioN Fig. 1. Center-of ... maes differential croae sections fro:. indicated laboratory ene;rSies. The insert shows the excitation curve for \ 0 the center-of-~ss angle, e = 56 • . .. · ... ·-~ ..... .. ,. ... -~ --..~--... l ! ~ 103~--~------~------~------~------~ 10 20. Blab .. 30 40 s1o3 ' •: ..J I> ... : .. :103 J " ~ ~ :' :;~ \ ~· . ' ~ ~ mJ I'll 0 : 0 0 0 0 0 0 0 G ~ 0 ~ ~ .6 0 ~-~-~ e ~ ~ ~ ~6 ~-a Ia m :; 10 2 1-T--r--r--.--r-r-"..,......,..--r--1 1 5 o m 00 I \ I \ i \ J .\ I \ 0 I \ I I 0 I I \ I <\ . \ ~ ~ ·~ ...... 100 ~ ~ ..c E 50 Fig. 1 41 MeV . A 0 . 0 e 0 0 jl02 e e 0 .0 0 0 10 · · 40 MeV12 0 . ~ ~ ~ ~ 10 e ~ C) 6• 6 6 10 40 50 This report was prepared as an account of Government sponsored work. Neither the United States, nor the Com~ mission, nor any person acting on behalf of the Commission: A. Makes any warranty or representation, expressed or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, appa-ratus, method, or process disclosed in this report may not infringe privately owned rights; or B. Assumes any liabilities with respect to the use of, or for damages resulting from the tise of any infor-mation, apparatus, method, or process disclosed in this report. As used in the above, "person acting on behalf of the Commission'' iricludes anj employee or contractor of the Com-mission, or employee of such contractor, to the extent that such empl~yee or con~ractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any inf~rm~tion pursuan~ to his employment or contract with the Commission, or his employment with such contractor. 

Elastic Alpha-Alpha Scattering Near 40 Mev

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ELASTIC ALPHA-ALPHA SCATTERING NEAR 40 Mev

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