Complete determination of the transition amplitudes from a comprehensive data analysis of the fusion reactions D(d,p)³H and D(d,n)³He for E_d<500 keV

Abstract

All relevant low-energy transition amplitudes for the D(d,n)'He and D(4p)'H reactions were determined from a fit to Legendre expansion coefficients of the available experimental data. A simple barrier penetrability model was used. Quintet S-wave transitions are found to contribute strongly thus obliterating the idea of neutron-lean "polarized" fusion energy production. The D + D interaction radius was determined with good accuracy for both reactions individudly. The astrophysical S functions show a small S-wave enhancement and Fwave suppression of the D (~f , p )~I f branch. Apart from possible applications the investigation of the D+D reactionswhich have received special interest from the beginning of nuclear reaction studiesis of interest in itself: the four-nucleon system is the lightest one exhibiting excited states. With the advent of faster computers and with the successes of rigorous theoretical calculations in the three-nucleon system e.g. 111 using modern meson-exchange potentials [2, 3, 4, 51 there is hope for realistic microscopic calculations (such as those based on Faddeev theory) also for this system, see e.g. [6]. The observed differences for the two branches of this system with identical particles in the entrance channel lend themselves to studies of the role of Coulomb interaction in the exit channel and possible charge-symmetry breaking effects. Comprehensive surveys of the four-nucleon system have been published recently [7, 81.On the other hand these fusion reactions play a role in nuclear astrophysics and furthermore they accompany the main reactions in planned light-particle fusion reactors. The economically advantageous concept of "neutron-lean" fusion energy production by using the 3He(d,p)4He reaction would only be realizable if the accompanying neutrons from the D(d,n)3He reaction could be suppressed. For this purpose the use of polarized "fuel" has been suggested where the neutron production via the entrancechannel spin-quintet states was assumed to be strongly suppressed [9, 101. This concept has been contradicted by some authors [11, 121 and will also be studied in this work.

Measurement of the polarization-transfer coefficientKyy'of the fusion reactionHImig1, Düweke2, Emmerich3 et al. 2006Phys. Rev. C6000View full textAdd to dashboardCite

“…7), the other the prediction from the T-matrix analysis using the results of Ref. [10] (see Fig. 8 from Ref.…”

“…V. Results for the D(d,n) 3 He reaction, not shown here, are 10% to 30% lower than for D(d,p) 3 H. For comparison only one early DWBA prediction for D(d,n) 3 He is shown here [16]. Theoretical predictions have been published in the framework of four-body Faddeev-Yakubovsky equations [14,22] and DWBA [16], whereas data parametrizations have used T-matrix analysis [10], R-matrix analysis [7,13], and phase-shift analysis [15].…”

“…Different from the 3 H(d,n) 4 He reaction and its mirror reaction 3 He(d,p) 4 He which are dominated at low energies by a 3 2 + S-wave resonant state they need 16 complex transition matrix elements (MEs) in S-, P-, and D-waves for a complete description. Using all available data of these reactions below E d = 1.5 MeV, parametrized by Legendre expansion coefficients, a set of MEs for each has been determined by direct fit [9][10][11][12]. This determination was practically model- * Corresponding author.…”

Highly Nuclear-Spin-Polarized Deuterium Atoms from the UV Photodissociation of Deuterium Iodide

“…Gj, 32.10.Fn Controlling the nuclear spin polarization in fusion reactions offers important advantages, such as larger reaction cross sections, control over the emission direction of products, and in some cases eliminating hazardous neutron emission [1,2]. In the case of the five-nucleon reactions D + T → n + 4 He and D + 3 He → p + 4 He, it is well known that the reaction cross section increases by ∼50% when the fused nuclei have oriented nuclear spins [3,4].For the 4-nucleon D+D reaction, over the important energy range of 10-100 keV, the situation is unclear, since several predictions range from enhancement of the reaction, suppression of the reaction, or almost no effect at all [5][6][7][8][9][10]. The technical challenges of measuring fusion polarization dynamics limits the number of experiments which pursue this direction to two facility-scale experiments [11].…”

“…For the 4-nucleon D+D reaction, over the important energy range of 10-100 keV, the situation is unclear, since several predictions range from enhancement of the reaction, suppression of the reaction, or almost no effect at all [5][6][7][8][9][10]. The technical challenges of measuring fusion polarization dynamics limits the number of experiments which pursue this direction to two facility-scale experiments [11].…”