INVESTIGATION OF THE REACTION 12C(14N, d)24Mg

(1)

HAL Id: jpa-00214864

https://hal.archives-ouvertes.fr/jpa-00214864

Submitted on 1 Jan 1971

HAL

is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire

HAL, est

destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INVESTIGATION OF THE REACTION 12C(14N, d)24Mg

H. Klapdor, N. Marquardt, H. Reiss

To cite this version:

H. Klapdor, N. Marquardt, H. Reiss. INVESTIGATION OF THE REACTION 12C(14N, d)24Mg.

Journal de Physique Colloques, 1971, 32 (C6), pp.C6-217-C6-218. �10.1051/jphyscol:1971646�. �jpa-

00214864�

(2)

JOURNAL DE PHYSIQUE Colloque C6, supplkment au no 1 1-12, Tome 32, Novembre-Dkcembre 1971, page C6-217

INVESTIGATION OF THE REACTION 2C(14N, d)2 4Mg

H. V. KLAPDOR, N. MARQUARDT and H. REISS Max Planck Institut fiir Kernphysik, Heidelberg, Germany

RbumB.

-

La reaction 12C(14N, d)24Mg a kt6 etudiee avec un faisceau de 14N5+ de 52 MeV.

Les distributions angulaires pour les &tats jusqu'a une Bnergie d'excitation de 25 MeV ont kt15 mesurees avec un spectrographe multi-angle. Les resultats preliminaires montrent que les Btats de haut spin excites preferentiellement dans les reactions (160, a) et ^(12C, a) sont Bgalement fortement excites dans la reaction (1 4N, d).

Abstract. -The reaction 12C(14N, d)24Mg has been studied using a 52 MeV 14N5+ beam.

Angular distributions for states up to 25 MeV excitation energy have been taken with a multigap spectrograph. The preliminary results show that the high spin states preferentially excited in (160, a) and (12C, a) are strongly populated also in the reaction (14N, d).

After the recent observation [I]-[4] of several narrow-width high-spin states in 24Mg a t excitation energies unbound to a-particle decay by

>

7 MeV by the reactions 160(12C, and 12C(160, a)24Mg it was of interest to study these states with other reactions to get some more insight into the structure of these states as well as into the excitation mechanism.

In the present paper we report on preliminary results of a study of the reaction 12C(14N, d)24Mg.

A

-

20 pg/cm2 12C target was bombarded with a 52 MeV 14N5+ beam from the Heidelberg MP tandem accelerator. Deuterons were recorded by nuclear track plates using a multigap spectrograph.

The energy resolution obtained by this method -

which we also used in a study of the reaction 12C(14N, 6 ~ i ) 2 0 N e (see another contribution to this Conference) - is between 60 and 120 keV. Angular distributions for states in the excitation region up to E* x 25 MeV in 24Mg have been taken in steps of 40-7.5O for lab angles between 00 and 900. The evaluation of these data is not yet completed. Figure 1 shows a part of a deuteron spectrum spanning the excitation energy range E* z 10-19 MeV. The differential cross sections for the strongest peaks at forward angles are 10 pb/sr showing that a 3-a-transfer in the reaction (12C -I- 14N) is at least a factor of five smaller than direct eight nucleon transfer [5]

at this bombarding energy. From figure 1 there is evidence that many more levels are excited in this reaction than in the reactions (160, a) and (12C, a).

Low lying states of 24Mg are generally very weakly excited. Several of the high spin states excited in (160, ^{E )}and (12C, a) are strongly populated also in the reaction (14N, d). SO the 14.14 MeV state which is known [6] to be the 8' member of the K = 2 rotational band, the 15.15 MeV state which is possibly [I]

FIG. 1. - Part of the deuteron spectrum for the reaction ^12C(14N,d)24Mg at a bombarding energy of

52 MeV and a lab angle of 5.50. Posit~on on Plate Fm]

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1971646

(3)

C6-218 H. V. KLAPDOR, N. MARQUARDT AND H. REISS

the 9+ member of the same band predicted [7] near also seen in the excitation region of the quasi-molecular E* ⁼16 MeV. Another candidate for this state states observed by Bromley et al. [9], the lowest of might be the 15.80 MeV level which is excited in them lying a t 19.2 MeV.

(14N, d) but not seen in (160, a) and (I2C, a). Further It is improbable that we excite the quartet states we excite the 16.59 MeV 6'-state and the 16.84 MeV recently predicted by Arima et al. [lo], because they level recently identified [8] as the 10+ member of the have Jn = 0, but an attractive alternative is the popu- ground state rotational band. Several states are lation of rotational structures built up on such states.

References [I] MIDDLETON (R.), GARRETT (J. D.), FORTUNE (H. T.),

Phys. Rev. Letters, 1970,24, 1436.

[2] GOBBI (A.), MAURENZIG (P. R.), CHUA (L.), HAD-

SELL (R.), PARKER (P. D.), SACHS (M. W.), SHAPIRA @.), STOKSTAD (R.), WIELAND (R.), BROMLEY (D. A.), Phys. Rev. Letters, 1971, 26, 396.

[3] GASTEBOIS (J.), BALLINI (R.), CHARLES (P.), FER-

NANDEZ (B.), FOUAN (J.), preprint, 1971.

[4] ZUR-E (R. W.), BALAMUTH (D. P.), BLUMEN-

THAL (D. A.), HOLDEN (J. E.), MIDDLETON (R.), NOE (J. W.), Bull. Am. Phys. Soc., 1970, 15, 1678.

[ 5 ] MARQUARDT (N.), VON OERTZEN (W.), WALTER (R. L.),

Phys. Letters, 1971, 35B, 37.

[6] BRANFORD (D.), GARDNER (N.), WRIGHT (I. F.), Proc. Montreal Conf., 1969, 112.

[7] AKIYAMA (Y.), ARIMA (A,), SEBE (T.), Nucl. Phys., 1969, A 138, 273.

[8] HADSELL (R.), et al., priv. corn.

[9] BROMLEY (D. A.), KUEHNER (J. A.), ALMQVIST (F.), Phys. Rev., 1961, 123, 878.

[lo] ARIMA (A.), GILLET (V.), GINOCCHIO (J.), Phys. Rev.

Letters, 1970, 25, 1043.