We report on the first measurement of spin-correlation parameters in quasifree electron scattering from vector-polarized deuterium. Polarized electrons were injected into an electron storage ring at a beam energy of 720 MeV. A Siberian snake was employed to preserve longitudinal polarization at the interaction point. Vector-polarized deuterium was produced by an atomic beam source and injected into an open-ended cylindrical cell, internal to the electron storage ring. The spin correlation parameter A V ed was measured for the reaction 2 H͑e, e 0 n͒ p at a four-momentum transfer squared of 0.21 ͑GeV͞c͒ 2 from which a value for the charge form factor of the neutron was extracted. [S0031-9007(99)09392-8] PACS numbers: 13.40. Gp, 14.20.Dh, 24.70. + s, 25.30.Fj Although the neutron has no net electric charge, it does have a charge distribution. Precise measurements [1] where thermal neutrons from a nuclear reactor are scattered from atomic electrons indicate that the neutron has a positive core surrounded by a region of negative charge. The actual distribution is described by the charge form factor G n E , which enters the cross section for elastic electron scattering. It is related to the Fourier transform of the charge distribution and is generally expressed as a function of Q 2 , the square of the four-momentum transfer. Data on G n E are important for our understanding of the nucleon and are essential for the interpretation of electromagnetic multipoles of nuclei, e.g., the deuteron.Since a practical target of free neutrons is not available, experimentalists mostly resorted to (quasi)elastic scattering of electrons from unpolarized deuterium [2,3] to determine this form factor. The shape of G n E as a function of Q 2 is relatively well known from high precision elastic electron-deuteron scattering [3]. However, in this case the cross section is dominated by scattering from the proton and, moreover, is sensitive to nuclear-structure uncertainties and reaction-mechanism effects. Consequently, the absolute scale of G n E still contains a systematic uncertainty of about 50%.Many of the aforementioned uncertainties can be significantly reduced through the measurement of electronuclear spin observables. The scattering cross section with both longitudinal polarized electrons and a polarized target for the 2 H͑e, e 0 N͒ reaction, can be written as [4]where S 0 is the unpolarized cross section, h the polarization of the electrons, and P d 1 (P d 2 ) the vector (tensor) polarization of the target. A e is the beam analyzing power, A V ͞T d the vector and tensor analyzing powers, and A V ͞T ed the vector and tensor spin-correlation parameters. The target analyzing powers and spin-correlation parameters depend on the orientation of the target spin. The polarization direction of the deuteron is defined by the angles Q d and F d in the frame where the z axis is along the direction of the three-momentum transfer (q) and the y axis is defined by the vector product of the incoming and outgoing electron momenta. A V ed ͑Q d 90 ±...

The reaction 16 O͑e, e 0 pp͒ 14 C has been studied at a transferred four-momentum ͑v, jqj͒ ͑210 MeV, 300 MeV͞c͒. The differential cross sections for the transitions to the ground state and the lowest excited states in 14 C were determined as a function of the momentum of the recoiling 14 C nucleus and the angle between the momentum of the proton emitted in the forward direction and the momentum transfer q. A comparison of the data to the results of calculations, performed with a microscopic model, shows clear signatures for short-range correlations in the 16 O ground state. [S0031-9007(98)07083-5] PACS numbers: 21.10. Pc, 21.30.Fe, 25.30.Fj, 27.20. + n In recent years, studies on short-range correlations (SRC) in nuclei have made striking progress. Microscopic many-body calculations in nuclear matter [1][2][3] and nuclei [4][5][6] have shown that SRC can account for a sizable fraction of the depletion in the occupancy of the valence orbits, observed in (e, e 0 p) proton knockout reactions [7]. Furthermore, these calculations predict an enhancement of the high-momentum components in the nucleon wave functions. Signatures of admixtures of highmomentum components in the nuclear ground state are expected to be found in the (e, e 0 p) reaction at high missing energies and in two-nucleon knockout (e, e 0 NN) studies [8,9]. Although experimentally more involved, the latter reactions have distinct advantages as a probe for studying SRC in nuclei.In an exclusive (e, e 0 NN) reaction both ejectiles are identified and the excitation energy of the residual nucleus is determined by energy conservation. This allows the measurement of the cross section for transitions to discrete states, as has recently been shown for the 16 O͑e, e 0 pp͒ 14 C reaction [10,11]. Furthermore, the reaction mechanism for two-nucleon knockout by virtual photons depends on the spin and isospin of the nucleon pair in the initial state. This implies that complementary information on SRC can be extracted from (e, e 0 pp) and (e, e 0 pn) reaction studies.In Ref.[10], we have presented the first results of a triple coincidence 16 O͑e, e 0 pp͒ 14 C experiment. The excitation energy spectrum up to 20 MeV of the residual nucleus 14 C and the corresponding missing-momentum distributions were compared with calculations performed within a simple factorization approximation of the cross section. In this Letter the differential cross sections are presented as a function of the excitation energy, the missing momentum, and the emission angle of the forward proton. The data are compared to the results of calculations performed with the microscopic model, recently described in Ref. [9].The measurements were performed with the high dutyfactor electron beam extracted from the pulse-stretcher AmPS at NIKHEF. The measurements were performed with 584 MeV electrons and the scattered electrons were detected at an angle of 26 ± . The central values of the energy transfer v and three-momentum transfer jqj were 210 MeV and 300 MeV͞c, respectively. Protons, with momenta p 1 a...

Purpose: GATE-RTion is a validated version of GATE for clinical use in the field of Light Ion Beam Therapy. This paper describes the GATE-RTion project and illustrates its potential through clinical applications developed in three European centers delivering scanned proton and carbon ion treatments. Methods: GATE-RTion is a collaborative framework provided by the OpenGATE collaboration. It contains a validated GATE release based on a specific Geant4 version, a set of tools to integrate GATE into a clinical environment and a network for clinical users. Results: Three applications are presented: Proton radiography applications at the Centre Antoine Lacassagne (Nice, France); Independent dose calculation for proton therapy at the Christie NHS Foundation Trust (Manchester, UK); Independent dose calculation system for protons and carbon ions at the MedAustron Ion Therapy center (Wiener Neustadt, Austria). Conclusions: GATE-RTion builds the bridge between researchers and clinical users from the OpenGATE collaboration in the field of Light Ion Beam Therapy. The applications presented in three European facilities using three completely different machines (three different vendors, cyclotron and synchrotron-based systems, protons and carbon ions) demonstrate the relevance and versatility of this project.

The reaction 16 O͑e, e 0 pp͒ has been studied at a transferred four-momentum ͑v, jqj͒ ͑210 MeV, 300 MeV͞c͒. Evidence has been obtained for direct knockout of proton pairs from the 1p shell. The excitation-energy spectrum of the residual nucleus and the missing-momentum densities indicate that knockout of a 1 S 0 pair dominates the reaction, while there is also a noticeable contribution from knockout of 3 P pairs. [S0031-9007(97) The description of short-range correlations (SRC) in complex nuclei is a long-standing problem in many-body physics. These correlations account for the effects of the nucleon-nucleon (NN) interaction at short distance and require a description of the dynamics of nucleons bound in a nuclear system that goes beyond the meanfield approach. Recently, several microscopic calculations of the momentum distribution of nucleons have been performed, both for nuclear matter [1][2][3] and nuclei [4,5], starting from realistic NN interactions. These calculations indicate that, due to the strong repulsive part of the NN force at short range, nucleons can scatter to energies and momenta far above the Fermi energy and momentum.If a nucleon of a strongly correlated pair is knocked out from a nucleus, e.g., after absorption of a virtual photon, the residual A 2 1 nucleus is likely to be left in a state with large excitation energy and momentum. As a consequence, the other nucleon may be emitted as well, which implies that information on SRC in nuclei can be obtained from studies of the semi-exclusive ͑e, e 0 N͒ reaction at large missing energy and momentum [6,7], or from the exclusive ͑e, e 0 NN͒ reaction. The latter reaction is expected to provide the most direct information on the effects of SRC, since in the plane wave impulse approximation (PWIA) its cross section is determined by the correlations in the relative wave function of the nucleon pair. Moreover, the identity of both emitted particles is determined, and the final state is well defined if the residual A 2 2 nucleus is left in its ground state or a low-lying excited state.Beyond PWIA, electromagnetically induced twonucleon knockout may also arise from coupling to mesonexchange currents (MEC) or result from D-excitation with subsequent decay via a DN ! NN reaction. Since SRC, MEC, and D-excitation contribute in a different way to the ͑e, e 0 pn͒ and ͑e, e 0 pp͒ reactions, these reactions are expected to yield complementary information on the different processes that contribute to the cross section.0031-9007͞97͞78(26)͞4893(5)$10.00