HAL Id: jpa-00230922
https://hal.archives-ouvertes.fr/jpa-00230922
Submitted on 1 Jan 1990
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.
POLARIZATION TRANSFER AND CHANNEL COUPLING EFFECTS IN (d,p) REACTIONS
H. Nakamura, K. Sagara, K. Maeda, S. Shimizu, T. Nakashima
To cite this version:
H. Nakamura, K. Sagara, K. Maeda, S. Shimizu, T. Nakashima. POLARIZATION TRANSFER AND CHANNEL COUPLING EFFECTS IN (d,p) REACTIONS. Journal de Physique Colloques, 1990, 51 (C6), pp.C6-459-C6-462. �10.1051/jphyscol:1990652�. �jpa-00230922�
POLARIZATION TRANSFER AND CHANNEL COUPLING EFFECTS IN ( d , p ) REACTIONS
H. NAKAMURA, K. SAGARA, K. MAEDA, S. SHIMIZU and T. NAKASHIMA
Department o f Physics, Faculty o f Science, Kyushu U n i v e r s i t y , Fukuoka 81 2 , Japan
Nous avons mesure les coefficients de transfert de polarisation pour la reaction (d,p) b 18 MeV sur les noyaux l2c, 2 8 ~ i , 'OC~, 5 2 ~ r et 9 0 ~ r et effectu6 des calculs en DWBA avec portee finie en utilisant l'interaction de Reid-Soft-Core. Le potentiel tenseur TR est essentiel pour les asymetrie tensorielles de la diffusion Qlastique, mais n'affecte aucune des variables de polarisation dans la r6action (d,p), pour lesquelles la caracteristique
"tenseur" de la polarisation vient essentiellement de l'btat D du deuton. Les coefficients de transfert de polarisation K:' de la reaction sur les noyaux deformes C et Si ne sont pas bien reproduiFs par la DWBA, mais, en equations couplees incluant l'btat D du deuton, K; est bien reproduit, tandis que l'accord pour K:; n'est pas am6lior8. D'autre part, une approximation adiabatique pour les noyaux spheriques reproduit bien K$; et d'autres coefficients de transfert de polarisation tensorielle b vectorielle.
abstract - The polarization transfer coefficients of the (d,p) reactions on the target nuclei of 1 2 c , 2 8 ~ i , 4 0 ~ a , 5 2 ~ r and were measured a t 18 MeV. Finite range DWBA calculation was carried out with the Reid soft core deuteron wave function.
T h e TR type tensor potential is essential t o the tensor analyzing powers of the elastic scattering. However, it is not affective t o any polarization observables in (d,p) reactions. The Tensor characteristics of these polarization observables are caused mainly by the deuteron D state. Polarization transfer coefficients K;' on deformed nuclei (C, Si) are not reproduced well in the DWBA calculation. In the channel coupling calculation including the deuteron D state, KZ' is reproduced well, while the fit t o K:: is not improved. On the other hand, a n adiabatic. approximation for the spherical nuclei can well reproduce KZ: and other tensor t o vector polarization transfer 'coefficients.
We have measured the polarization transfer coefficients ( PTC's ) on several (d,p) reactions together with the vector and tensor analyzing powers of the (d,p) reactions and of the corresponding deuteron elastic scattering. Some kind of PTC's has a simple meaning. In a simple model, a dip of K;' shows the deuteron D state contribution./l/
Some formalisms of spin observables/2/,/3/ predict K& is caused by tensor interactions such as the TR tensor potential and the deuteron D state. However, few measurement has been done on the PTC's in
(dip)
reaction of medium heavy nuclei. We have measured the PTC's in ''C (dlp)13C (312-, gnd.st.), ''C (dlp)13C (1/2+, 3.09MeV)/4/, 28Si (d,P)2gSi (1/2+, gnd.st.)/4/ 40Ca (d,p)41Ca (712-, gnd.st.)/5/, 52Cr ( d , ~ ) ~ ~ C r (312-, gnd.st.)/6/, 9 0 ~ r (d,p)glZr (5/2+(, gnd.st.)/7/ and " ~ r (d,p)glZr (1/2+, 1.20MeV)/7/ a t the deuteron energy of 18 MeV.In our analysis, we would like to find which observables are sensitive to the tensor effects, such as the effect of the TR potential and the deuteron D state, break up and the channel coupling. The TR potential, with a strength of a half to one third of the potential predicted by folding model, is necessary to reproduce A,, and X, of the elastic scattering. For the (d,p) reaction, however, the , ?' potential has no effect for both of the analyzing powers and the PTC's. Fig. 1 shows the PTC's in 40Ca(d,p) and DWBA calculations with or without the D state. In this case, most of the PTC's are
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1990652
C6-460 COLLOQUE DE PHYSIQUE
reproduced well in the finite range DWBA using the Reid soft core wave function for the deuteron. DWBA calculation with the S state only does not account for K;"S dip and K$ at all. Even with the D state, K:; and K& are not reproduced well.
Next, a n adiabatic approximation/8/ with global potentials/9/ for proton and neutron was tested. The results are also shown in Fig. 1 together with DWBA ones.
This simple calculation surprisingly well reproduces PTC's, especially K;; and K$. Fig.
2 and Fig. 3 show the case of 52Cr(d,p) and gOZr(d,p), respectively. These (dip) reactions have a similar tendency t o the case of 40Ca(d,p). This fact may mean that thr tensor t o vector PTC's depend on the deuteron break up effect.
In the deformed nuclei case, the inelastic scattering becomes more important. So, a channel coupling calculation must be needed. In order to accounting for the deuteron D state effect, amplitudes of a channel coupling calculation with the S state of the deuteron and ones of a single step calculation of the corresponding transition with the deuteron D state are added incoherently. Fig. 4 shows the channel coupling calculation with and without the D state in the cases of 12C(d,p) and 28Si(d,p), together with the results in a conventional DWBA calculation for comparison. By the channel coupling calculation, second dips of K;' in both cases are reproduced better than by a DWBA calculation. However, tensor t o vector PTC's such as K:;-. and KZ: - K:: are left worse.
In summary, first, the TB type tensor potential does not play so important role in the (d,p) reaction as in the elastic scattering. Second, the tensor effect are mainly introduced as the deuteron D state effect, as was shown in the spherical nuclei cases.
From the adiabatic calculation, the observables which were not described well in DWBA, especially K:; and K&, may reflect well the deuteron break up effects. This should be confirmed by more rigorous treatment such as CDCC. For the deformed nuclei, the channel coupling calculation well reproduces K;' but fails for the tensor to vector PTC's, such as K & .
Fig. 1. PTC's in 40Ca(d,p) reaction at 18 MeV. Solid curves are DWBA calculation with deuteron S+D state and dashed curves with S state only. Dotted curves are adiabatic calculation. Errors in experimental data indicate statistical ones only.
1.5r1 "'\W SF...-- r ti;
. : ; j.:: '-'
Fig. 2. PTC's in "cr(d,p)( 312-, gnd. st.) reaction at 18 MeV. Solid curves are DWBA calculation and dotted curves adiabatic calculatiopn.
2. 0
0 0
- 2 . 0 -3 0 " " " " " " " " '
0 9 0 180 0 90 0 9 0 1 8 0 0 9 0 1 8 0
Fig. 3. PTC's in g0~r(d,p)(5/2+, gnd. st.) (left hand side) and 90~r(d,p)(1/2+, 1.20MeV) (right hand side) at 18 MeV. curves are same as in Fig. 2.
C6-462 COLLOQUE DE PHYSIQUE
Fig. 4. PTC's in 12~(d,p)(l/2C,3.09 MeV)(left hand side) and "~i(d,p)(l/2+, gnd.
st.)(right hand side) a t 18 MeV and 17.8 MeV, respectively. Solid curves are channel coupling calculation with S f D state and dashed curves are with S state only. Dotted curves are conventional DWBA calculation.
references /l/ Basak, A. K. et al., Nucl. Phys. A275 (1977) 381.
/2/ Santos, F. D., Nucl. Phys. A236 (1974) 90.
/3/ Tanifuji, M. and Yazaki, K., Prog. Theor. Phys. 40 (1968) 1023.
/4/ Maeda, K. et al., contribution t o this conference (43B) /5/ Nakamura, H. et al., contribution t o this conference (49B) /6/ Maeda, K.et al., contribution t o this conference (44B) /7/ Shimizu, S. et al., contribution t o this conference (75B) /8/ Johnson, R. C. and Soper, P . J . R., Phys. Rev. C1 (1970) 976.
/g/ Becchetti, F. D. and Greenlees
