F. N. Rad

Performance of a silicon proton polarimeter between 19 and 32 MeV

Abstract The design is presented of a proton polarimeter which combines the advantages of high scattering efficiency and good energy resolution. The polarimeter, intended for proton energies above 17 MeV, is well-suited to the study of polarisations in low-yield reactions and has been used in the measurement of triple-scattering parameters. A typical figure of merit Aσ 1 2 of ≈ 2.2 × 10 −3 and an energy resolution of approximately 100 keV fwhm at 26 MeV make the present type of polarimeter superior to others for experiments where good energy resolution is required.

Extreme values of the spin polarization analyzing power in nuclear reactions

Abstract States of maximum possible polarization are investigated for ensembles of spin- 1 2 and spin-1 particles in nuclear reactions. General criteria for extreme values of some components of the analyzing power are given and applied to the formulae for the observables of reactions with various spin spaces. Experimental data relevant to possible extreme values are discussed.

Measurement of the Proton Analyzing Power in the p-d Breakup Reaction

We report in this paper on the measurement of the proton analyzing power Ay in the 2H(,p)d* reaction at Ep = 22.7 MeV,}which corresponds to the same center of mass energy as that in the 1H(,p)d* reaction reported by Conzettl) Here, d* denotes final-state np pairs with relative energy Enp ≤ 1 MeV, in both the singlet and triplet states. Previously there had been measurements of the vector analyzing power in the 2H(,2p)n (ref.2) and 1H(,2p)n (ref.3) transitions to the np final-state interaction (FSI) region at Ep = 10.5 MeV and Ed = 12.2 MeV, respectively. In both instances the analyzing powers were very small or consistent with zero. The higher energy results at Ed = 45.4 McV1) showed values of Ay reaching 0.15±0.02. The exact three-body calculations4,5), which have been successful in fitting N-d breakup cross sections, have so far been limited to S-wave N-N input interactions and, thus, provide no polarization.

Extreme Values of the Analyzing Power for Spin-1 Polarization

The large experimental values of the components Ay and Ayy of the analyzing power for deuterons in several processes suggest the possibility of extreme values Ay = ± 1 and Ayy = 1. Criteria to judge maximum possible polarization states for an ensemble of polarized spin-1 particles produced in a nuclear reaction have been given by Lakin1) and Minnaert2). They are based on the fact that the density matrix is positive semidefinite. Its expansion in terms of tensor operators τkq imposes conditions on the tensor moments tkq. Due to time reversal invariance, identical limitations apply for the polarization efficiencies tkq. They are particularly simple in a transverse coordinate system S′ with the z′-axis perpendicular to the reaction plane.

The Vector Analyzing Power in the 2H(\(\overrightarrow d \) ,p)3H Reaction between 15 and 25 MeV

The charge-symmetric reactions 2H(d,p)3H and 2H(d,n)3He have been studied in considerable detail at energies up to 15 MeV1,2). Differential cross sections, nucleon polarizations, and deuteron vector and tensor analyzing powers have been measured, and differences in these observables for the two reactions have been examined for evidence of a possible deviation from the charge symmetry of the nuclear interactions. The more recent comparisons and calculations3) have been able to explain the observed differences between the two reactions in terms of the Coulomb effect, including the Q-value difference.

Points of Maximum Analyzing Power in the \({}^3He(\vec d,p){}^4He\) Reaction

The \({}^3He(\vec d,p){}^4He\) reaction has been the first process, other than elastic scattering, in which a point (Eo,θo) of maximum possible tensor analyzing power Ayy = 1 has been proposed1). An inspection of the complete deuteron polarization data of Gruebler et al.2) at 11.5 MeV and of the i T11 measurements of Roy et al.3) at 15 MeV indicates the possibility of large positive values of both Ay and Ayy near θcm = 120° and thus of a point Ay = Ayy = 1 between these energies. The necessary but not sufficient conditions Axx = Azz =−1/2 and Axz = 0 are nearly fulfilled at 11.5 MeV1,4). Unfortunately these tensor observables are not available at higher energies. For the investigation and possible identification of such a point, the relevant conditions on the M-matrix have to be verified. Using the presentation5,6,7)

Vector Analyzing Power in the \({}^3He(\vec d,{}^3He)np\) Reaction

M = \frac{1}{{\sqrt 2 }}\left( {\begin{array}{*{20}{c}} { - iA - D \sqrt 2 F - iA + D - B - C \sqrt 2 E - B + C} \\ {B - C{\text{ }}\sqrt 2 E{\text{ }}B + C{\text{ }} - iA + D{\text{ }}\sqrt 2 F{\text{ }} - iA - D} \end{array}} \right)

Polarization effects in the final-state interaction region of the p--d breakup reaction

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