Measurement of the Angular Distribution of Tensor Polarization in Pion-Deuteron Elastic Scattering

Holt, R. J.; Specht, Janet K.; Stephenson, K.; Zeidman, B.; Frank, James S.; Leitch, M. J.; Moses, J. D.; Stephenson, E.J.; Laszewski, R.M.

doi:10.1103/physrevlett.47.472

Cited by 67 publications

(4 citation statements)

References 12 publications

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“…2, where errors are statistical only. Similar data from other experiments 12 * 14,18,19 are also shown for comparison. The most striking feature of the data is the appearance of a clear dip-bump structure; there are two dips around 630 and 980 MeV/c, and two bumps in the vicinity of 670 and 1100 MeV/c.…”

Section: Unscattered Beamsupporting

confidence: 72%

Confirmation of Dip-Bump Structure in Backwardπ−−dElastic Scattering: Possible Evidence for Dibaryon Resonances

Akemoto

Endo

et al. 1983

Phys. Rev. Lett.

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The backward differential cross section for TT~-d elastic scattering has been measured at incident momenta between 420 and 1160 MeV/c. The data show two bumps at around 670 and 1100 MeV/c, two dips near 630 and 980 MeV/c, and a break at 550 MeV/c. The result of a phenonomenological fit is consistent with the existence of three dibaryon resonances in this energy region. A theoretical calculation of Kanai et al. agrees well with the data below 800 MeV/c, but the agreement becomes worse above 800 MeV/c.

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Section: Unscattered Beamsupporting

confidence: 72%

Confirmation of Dip-Bump Structure in Backwardπ−−dElastic Scattering: Possible Evidence for Dibaryon Resonances

Akemoto

Endo

et al. 1983

Phys. Rev. Lett.

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“…Since a description of this polarimeter has been presented by Holt et al 8 and a simpler prototype was discussed in detail by Stephenson etal.,9 only a brief description of the polarimeter will be given here. The polarimeter makes use of the reaction 3 He(d,p) 4 He which is known to have a large cross section and analyzing power for t 20 at forward reaction angles.…”

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confidence: 99%

Measurement of the Tensor Polarization in Electron-Deuteron Elastic Scattering

Beck²,

et al. 1984

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This paper reports the first measurement of the tensor polarization t 2 o ine-d elastic scattering. The polarization of the recoil deuterons was measured for two values of momentum transfer, # = 1.74 and 2.03 fm" 1 , with a high-efficiency polarimeter. The results are in good agreement with reasonable models for the deuteron.PACS numbers: 25.30.Bf, 24.70,+ s, 25.10.+ S A complete experimental determination 1 ' 2 of the electromagnetic current of the deuteron requires the measurement of at least one polarization observable, in addition to the differential cross section. Here we report the first measurement of t 20 in elastic e-d scattering. Measurements of t 20 have previously not been feasible because of the absence of high-efficiency deuteron tensor polarimeters or tensor-polarized targets, and the lack of high-intensity electron beams and large-acceptance magnetic spectrometers. The results are found to be in good agreement with the predictions of t 20 for "reasonable" models of the deuteron, but in disagreement with those of separable-potential models.Electron elastic scattering from the deuteron can be described by three form factors: charge (F c ), quadrupole (FQ), and magnetic (F M ). Thus far, only F M has been isolated 3 in measurements of the cross section. The form factors F c and F Q have not been isolated previously from measurements of the structure function. 4 A determination of these form factors separately would discriminate further among different deuteron wave functions. The sensitivity of t 20 to the deuteron wave function arises from the fact that the leading term in t 2Q is proportional to the ratio of F Q to F c . in this ratio, the poorly known isoscalar electric nucleon form factor drops out. The expression for t 2Q is given 2 by t 20 2 , and/(6>) = i + (l+77)tan 2 (6i/2). Here, q is the four-momentum transfer, M d is the rest mass of the deuteron, and 6 is the angle of the scattered electron. The terms involving powers of X in the numerator are dominant in the momentum transfer region of 1-5 fm" 1 . Thus, t 20 is sensitive to the ratio of F Q to F c . The quantity F Q is sensitive to the tensor part of the N-N interaction, while F c is dominated by the S-wave part of the deuteron wave function at these values of low momentum transfer. Additionally, recent work 1 ' 2 has shown that t 2Q is also sensitive to the isoscalar meson exchange current (MEC) and relativistic corrections, about which there is much controversy. 5 The experiment was performed at the South Experimental Hall of the Massachusetts Institute of Technology-Bates Linear Accelerator Center. A schematic diagram of the experimental arrangement is given in Fig. 1. The electrons from the linac were focused on a windowless D 2 0 target which consisted of a 0.38-or 0.64-mm-thick laminar flow of heavy water. The incident electron energies were 371 ±2 MeVfor ^r=2.03fm" 1 , and 310± 1.8 MeVfor #=1.74 fm" 1 . During the experiment the average current and duty factor of the electron beam varied from 15 to 50 /iA and 0.3% to 0.4%, respec...

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“…The pion-deuteron scattering experiments [1,2,3,4] were performed at LAMPF. These early experiments made use of a tensor polarimeter based on the 3 He(d,p) 4 He reaction.…”

Section: Pion and Electron Scattering Experimentsmentioning

confidence: 99%

From the nucleus to the quarks

Holt¹,

Arrington²,

Melnitchouk³

2010

AIP Conference Proceedings

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Rare pion double radiative capture reactions on hydrogen and deuterium AIP Conf. Abstract.Early work by A. W. Thomas and his colleagues inspired the first measurements of polarization in pion-deuteron elastic scattering. This line of research and technology developments enabled polarization experiments in electron-deuteron elastic scattering as well as the widespread use of polarized internal targets in storage rings. These ideas and techniques are now being used to study two-photon exchange effects and to make progress toward experiments that will allow for improved extractions the d u ratio at high x.

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Measurement of the Angular Distribution of Tensor Polarization in Pion-Deuteron Elastic Scattering

Abstract: The angular dependence of the deuteron tensor polarization £ 2 o m n~d elastic scattering has been measured for the first time. The results, at an incident pion energy of 142 MeV, are found to be in disagreement with all present theoretical predictions.

Cited by 67 publications

References 12 publications

Confirmation of Dip-Bump Structure in Backwardπ−−dElastic Scattering: Possible Evidence for Dibaryon Resonances

Confirmation of Dip-Bump Structure in Backwardπ−−dElastic Scattering: Possible Evidence for Dibaryon Resonances

Measurement of the Tensor Polarization in Electron-Deuteron Elastic Scattering

From the nucleus to the quarks

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