Is the 12C(,d0) reaction a good polarization standard?

Arvieux, J.; Bírchall, J.; Conzett, H.E.; Dahme, W.; Haeberli, W.; Larimer, R. M.

doi:10.1016/0029-554x(74)90851-9

Cited by 4 publications

(7 citation statements)

References 7 publications

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“…Astonishing agreement was observed between central energies E 0 , resulting from the fit, and energies of resonances in the reaction 12 C(d, α 2 ) 10 B with population of the second excited state in 10 B given in an earlier data compilation of [47] and the actual one [48] with reference to [45]. The reaction is understood as including intermediate 14 N states. The deuteron resonance energies, the corresponding energies of exited 14 N states, and spin/parity of these states are given in columns 8, 9, and 10 of the tables.…”

Section: Modeling Pzz(ein) Of the Transmitted Beamsupporting

confidence: 70%

“…The theoretically predicted weak, smooth effect of nuclear dichroism gets superposed by these rapid fluctuations. Such fluctuations were also observed in the elastic scattering of polarized deuterons on 12 C in the energy range 20 to 30 MeV [13,14]. It was mentioned there that inconsistencies in the description of the measured vector analyzing powers in the framework of the optical potential [15] might be due to the creation of intermediate excited states in 14 N. The angular distributions of low-energy deuteron induced reactions on 12 C with beam energies of 2.502 and 2.735 MeV had also been interpreted with creation of intermediate excited states in 14 N [16].…”

Section: Introductionmentioning

confidence: 74%

“…Such fluctuations were also observed in the elastic scattering of polarized deuterons on 12 C in the energy range 20 to 30 MeV [13,14]. It was mentioned there that inconsistencies in the description of the measured vector analyzing powers in the framework of the optical potential [15] might be due to the creation of intermediate excited states in 14 N. The angular distributions of low-energy deuteron induced reactions on 12 C with beam energies of 2.502 and 2.735 MeV had also been interpreted with creation of intermediate excited states in 14 N [16]. Due to the relation between the analyzing power and the polarization in the inverse reaction [17], the fluctuations observed in the analyzing power are to be expected in the polarization of an unpolarized beam, too.…”

Section: Introductionmentioning

confidence: 74%

“…In the ground state 14 N is of prolate deformation with Q 0 = (1.93 ± 0.08) fm 2 [47]. As no data were found for the excited states around 23 MeV, the assumption is made that the excited nucleus oscillates around the ground-state shape.…”

Section: A Coarse Structurementioning

confidence: 99%

“…This indicates that in the 12 C(d, n) 13 N g.s. reaction,too, the formation of intermediate excited 14 N states leads to the enlargement of the reaction cross section. Besides direct proton pick-up, this possibility was discussed in [58] without, however, a definite conclusion.…”

Section: A Coarse Structurementioning

confidence: 99%

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Rapid fluctuation of the tensor polarization of deuteron beams behind carbon foils and their relation to the resonances in the isospin-breaking $^{12}{\rm C}(d,α_{2})^{10}{\rm B}^{*}$ reaction

Seyfarth,

Rouba,

Baryshevsky

et al. 2017

Preprint

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Rapid fluctuations are observed in the tensor-polarization pzz of deuteron beams forwardtransmitted through graphite targets. Unpolarized 9.50 to 18.60 MeV beams from the Köln tandem accelerator were utilized, and the polarization behind seven 36 to 188 mg/cm 2 targets was measured with a polarimeter based on the 3 He( d, p) 4 He reaction. Due to the chosen relation between the areal target densities and the initial beam energies Ein, the seven sets of pzz(Ein) can be combined in a common plot as a function of Ein. This allows one to understand pzz, measured behind the 188 mg/cm 2 target at Ein=18.6 MeV, as resulting from the sequence of differential polarization production ∆pzz(E)/∆E during energy degradation in the target from E=18.60 to 9.50 MeV. The rapid fluctuations of ∆pzz(E)/∆Epzz are described by 51 Gaussian-distributed cross-sections removing deuterons either in the m = 0 or in the m = ±1 state from the beam. The 51 fitted central energies E0 with a single exception agree with the energies of the narrow peaks in the excitation functions of the weak, isospin-breaking 12 C(d, α2) 10 B * (1.74 MeV, J π = 0 + , T = 1) reaction with population of the second excited 10 B state via intermediate excited 14 N states. Angular momentum and parity conservation confines their spin values to J = l, the orbital angular momentum in the entrance state. Formation of J = l ± 1 states with other decay channels would be possible. According to the fit result, formation of J = l excited 14 N states dominates in the removal of deuterons from the beam. The coarse energy dependence of the present fluctuations corresponds to the excitation of the 14 N giant electric dipole resonance, split into regions of ∆pzz(E)/∆E >0 and <0. Strong evidence is found that removal of deuterons in the m = 0 (m = ±1) state from the beam leads to the formation of 14 N states of established positive (negative) parity. As an application, the removal cross-section functions allow to calculate pzz achievable with carbon targets for initial beam energies Ein between 18.60 and 9.50 MeV and Eout given by the areal target density. Carbon layers in a sandwich technique would enable pzz between -0.4 and +0.3.

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Section: Modeling Pzz(ein) Of the Transmitted Beamsupporting

confidence: 70%