K.I. Blomqvist

A cryogenic tritium target system for nuclear physics experiments

Abstract A cryogenic tritium ( 3 H 2 ) gas target system was constructed and used for a program of electron scattering studies. The 3 H 2 was supplied and safely stored as solid U 3 H 3 . For the experiments, it was transferred to a thin walled cylindrical cell, where it was exposed to 25 μA electron beams with energies up to 800 MeV. During operation, the target cell contained 115000 Ci of tritium at 225 psia and 45 K. Multiple safety enclosures surrounded both target and gas transfer systems. A microprocessor-based control and monitoring system presented target parameters to the operators, identifying those out of range. The target system operated safely and effectively for about 2000 h, enabling completion of comprehensive elastic and elastic electron scattering study of the three nucleon system.

Trinucleon Threshold Electrodisintegration

Inclusive inelastic electron scattering cross sections for 3H and 3He were measured for excitation energies below 18 MeV. For six values of the three-momentum transfer q in the range 0.88 < q < 2.87 fm−1, longitudinal and transverse response functions were determined. The experimental data are in good agreement with two recent calculations. One uses variational ground-state wave functions and the orthogonal correlated states method to describe the two- and three-body breakup channels. The other uses bound and continuum Faddeev wave functions for a simple central potential. The inclusion of final-state interactions (FSI) in the Faddeev continuum is found to be very important; inclusion of FSI changes the response functions in the threshold kinematics by a large amount, yielding excellent agreement with the data.

Pion Spectra to Individual Final States in the Reactions 12C(γ,π±)12B, 12N

The cross sections for the reactions 12C(γ,π+)12B and 12C(γ,π−)12N to various states of the final nucleus have been measured at a pion energy around 29 MeV for electron energies from 187 to 193 MeV, and at a pion energy around 17 MeV with electron energies from 174 to 181 MeV, and at a pion angle 90° with respect to the incident photon beam. The observed states in 12B and 12N are the analogues of T = 1 states in 12C which are excited by inelastic electron scattering1,2. Furthermore, the (γ,π) one-body operator tends to strongly excite spin-flip components of the transitions to these states.

Inclusive Electroproduction of Low Energy Pi Mesons

Because the electromagnetic interaction is well known and because the real or virtual photon can create a pion at any point inside the target nucleus, the study of gamma-pi type experiments can give important information concerning the final state interaction of the pion with the daughter nucleus.