Measurement ofT20for the ReactionH1

Abstract

The tensor analyzing power T 2 Q for the radiative capture reaction 1 H (d po] ,y) 3 HQ has been measured in order to test new three-body wave functions. This observable arises from the D state of 3 He. An effective two-body direct-capture calculation, which was previously shown to fit the a 2 coefficient of a Legendre-polynomial expansion of the differential cross section, is found to give a good description of the present data. A value for the asymptotic D/S ratio is extracted from the data although it is found to be model dependent.PACS numbers: 21.40.-hd, 24.70. + s, 25.45.-z, 27.10. + h Recent theoretical calculations of few-body wave functions have stimulated interest in new measurements on very light nuclei. In particular several related reactions have been used to study the ground state of 3 He. Among these are photodisintegration 1 ' 2 and electrodisintegration 3 of 3 He and radiative capture of protons by deuterons 4 " 6 and of deuterons by protons. 7 The a 2 coefficient of a Legendre-polynomial expansion of the differential cross section for y-ray emission following capture of protons by deuterons has been found sensitive to the Z)-state component of the 3 He ground-state wave function. 5 As pointed out by Seyler and Weller, 8 the tensor analyzing powers of the reaction 1 H(rf pol ,y) 3 He are expected to be more sensitive to ZXstate effects. In fact they are identically zero if the S= y capture amplitude, which arises from the D state, is absent. Of the previous work only Ref. 6 involves a polarized beam, the incident particles being protons. Therefore, it is important that experiments be done with a polarized deuteron beam. Measurements of r 20 , with good statistical accuracy, have been performed for the reaction l H(d poh y) 3 He and are reported in this Letter. An effective two-body radiative-capture calculation, similar to the one used in Ref. 5 to describe the differential cross section, fits the present data well. In addition, an upper limit of 0.050 for the asymptotic D/S state ratio 17 is implied by the data.The deuteron beam used in this reaction produces a high neutron flux which makes it difficult to detect the y rays. To avoid this problem the recoiling 3 He nuclei were detected instead with an Enge split-pole spectrograph. A one-to-one relationship exists between the energy of the 3 He and the angle of the y ray (Fig. 1). However, for the beam energy used, the 3 He nuclei are confined to a cone about the beam axis with a maximum angle of 2.6°; the beam particles are therefore in the way. An appropriate magnetic field was chosen such that the beam was collected in a Faraday cup at a large radius of curvature R in the spectrograph, while the 3 He particles were separated magnetically and focused at low R. The McMaster University Lamb-shift polarized-ion source was used to produce polarized deuterons alternatively in the m = 1 and m = 0 substates relative to the beam direction. An energy of 19.8 MeV was used. The target was a polyethylene (CH 2 ) film approximately 100 /ng/cm 2 thick. The ...

Manifestations of the D-State in Light Nuclei

“…In order to increase the sensitivity of the capture reaction measurements to the D state component of 3He, the tensor analyzing power fo r the IH( J ,y)3He reaction was measured (79). In particular, the spherical TAP T20(e) was determined at Ed = 19.7 MeV as a function of e. This quantity is given by 14.…”

Vector and tensor analyzing powers of theH1(d→Klechneva1, Carasco2, Goussev3 et al. 2006Phys. Rev. C5100View full textAdd to dashboardCite

“…As will be discussed in the last section the tensor analyzing power at these two energies has rather different sensitivities to the underlying physics. As a third extension we also measured the data of the deuteron vector analyzing power A The data points are from [12,14,15,16,17,18]. The dashed line represents the Faddeev calculation by Golak et al [2] II.…”

Trinucleon Photo-Reactions with Δ-Isobar Excitation: Radiative Nucleon-Deuteron Capture and Two-Body Photo-Disintegration of the Three-Nucleon Bound State

“…The spin observable T20 is shown on the bottom; the experimental data are taken from ref. [26]. The full results for the interaction with ∆-isobar excitation are shown as solid lines, whereas the results for the purely nucleonic reference potential, the Paris potential, are shown as dashed lines.…”

“…In the figures we follow the standard convention for the presentation of data as introduced in refs. [25][26][27]: At 19.8 MeV the c.m. photon angle refers to the direction of the proton, i.e., it is the c.m.…”