pi-NN Coupling Constants from NN Elastic Data between 210 and 800 Mev

High partial waves for $pp$ and $np$ elastic scattering are examined critically from 210 to 800 MeV. Non-OPE contributions are compared with predictions from theory. There are some discrepancies, but sufficient agreement that values of the $\pi NN$ coupling constants $g_0^2$ for $\pi ^0$ exchange and $g^2_{c}$ for charged $\pi$ exchange can be derived. Results are $g^2_0 = 13.91 \pm 0.13 \pm 0.07$ and $g^2_c = 13.69 \pm 0.15 \pm 0.24$, where the first error is statistical and the second is an estimate of the likely systematic error, arising mostly from uncertainties in the normalisation of total cross sections and $d\sigma/d\Omega$.Comment: 21 pages of LaTeX, UI-NTH-940

Lump correction and identification in the combined thermal/epithermal neutron (CTEN) method

The authors present a model for self shielding in lumps of fissile material in active-neutron assays. The model combines the formula for self-attenuation of gamma-ray in lumpy sources with the multi-group analysis techniques used in neutron transport calculations. Models for thin foils and for spheres are examined in terms of error multiplication in determining lump corrections and the basic accuracy of the model

Aqueous Solution Chemistry of Ammonium Cation in the Auger Time Window

We report on chemical reactions triggered by core level ionization of ammonium NH4 cation in aqueous solution. Based on a combination of photoemission experiments from a liquid microjet combined with high level ab initio simulations, we identified simultaneous single and double proton transfer occurring on a very short time scale spanned by the Auger decay lifetime. Molecular dynamics simulations indicate that the proton transfer to a neighboring water molecule leads to essentially complete formation of H3O aq and core ionized ammonia NH3 amp; 8270; aq within the 7 fs lifetime of the nitrogen 1s core hole. A second proton transfer leads to a transient structure with the proton shared between the remaining NH2 moiety and another water molecule in the hydration shell. These ultrafast proton transfers are stimulated by very strong hydrogen bonds between the ammonium cation and water. Experimentally, the proton transfer dynamics is identified from an emerging signal at the highkinetic energy side of the Auger electron spectrum in analogy to observations made for other hydrogenbonded aqueous solutions. The present study represents the most pronounced charge separation observed upon core ionization in liquids so fa

Torsion and vibration-torsion levels of the S1 and ground cation electronic states of para-fluorotoluene

We investigate the low-energy transitions (0–570 cm-1) of the S1 state of para-fluorotoluene (pFT) using a combination of resonance-enhanced multiphoton ionization (REMPI) and zero-kinetic-energy (ZEKE) spectroscopy and quantum chemical calculations. By using various S1 states as intermediate levels, we obtain zero-kinetic-energy (ZEKE) spectra. The differing activity observed allows detailed assignments to be made of both the cation and S1 low-energy levels. The assignments are in line with the recently-published work on toluene from the Lawrance group [J. Chem. Phys. 143, 044313 (2015)], which considered vibration-torsion coupling in depth for the S1 state of toluene. In addition, we investigate whether two bands that occur in the range 390–420 cm-1 are the result of a Fermi resonance; we present evidence for weak coupling between various vibrations and torsions that contribute to this region. This work has led to the identification of a number of misassignments in the literature, and these are corrected

Vibrational and vibrational-torsional interactions in the 0–600 cm-1 region of the S1 ← S0 spectrum of p-xylene investigated with resonance-enhanced multiphoton ionization (REMPI) and zero-kinetic-energy (ZEKE) spectroscopy

We assign the 0–600 cm-1 region of the S1 ← S0 transition in p-xylene using resonance-enhanced multiphoton ionization (REMPI) and zero-kinetic-energy (ZEKE) spectroscopy. In the 0–300 cm-1 range, as well as the intense origin band there are a number of torsional and vibration-torsion (vibtor) features. The latter are discussed in more detail in an accompanying paper [Gardner et al. J. Chem. Phys. XXX, xxxxxx (2016)]. Here we focus on the origin and the 300–650 cm-1 region, where vibrational bands and some vibtor activity is observed. From the origin ZEKE spectrum we derive the ionization energy of p-xylene as 68200 ± 5 cm-1. The assignment of the REMPI spectrum is based on the activity observed in the ZEKE spectra coupled with knowledge of the vibrational wavenumbers obtained from quantum chemical calculations. We assign several isolated vibrations, and a complex Fermi resonance that is found to comprise contributions from both vibrations and vibtor levels, and we examine this via a two-dimensional ZEKE (2D-ZEKE) spectrum. A number of the vibrational features in the REMPI and ZEKE spectra of p-xylene that have been reported previously are reassigned and now largely consist of totally-symmetric contributions. We briefly discuss the appearance of non-Franck-Condon allowed transitions. Finally, we find remarkably similar spectral activity to that in the related disubstituted benzenes, para-difluorobenzene and para-fluorotoluene

Full configuration interaction calculation of BeH adiabatic states

An all-electron full configuration interaction (FCI) calculation of the adiabatic potential energy curves of some of the lower states of BeH molecule is presented. A moderately large ANO basis set of atomic natural orbitals (ANO) augmented with Rydberg functions has been used in order to describe the valence and Rydberg states and their interactions. The Rydberg set of ANOs has been placed on the Be at all bond distances. So, the basis set can be described as 4s3p2d1f/3s2p1d(Be/H)+4s4p2d(Be). The dipole moments of several states and transition dipole strengths from the ground state are also reported as a function of the RBe–H distance. The position and the number of states involved in several avoided crossings present in this system have been discussed. Spectroscopic parameters have been calculated from a number of the vibrational states that result from the adiabatic curves except for some states in which this would be completely nonsense, as it is the case for the very distorted curves of the 3s and 3p math states or the double-well potential of the 4p math state. The so-called “D complex” at 54 050 cm−1 (185.0 nm) is resolved into the three 3d substates (math,math,math). A diexcited valence state is calculated as the lowest state of math symmetry and its spectroscopic parameters are reported, as well as those of the 2 math (4d) state The adiabatic curve of the 4 math state shows a swallow well at large distances (around 4.1 Å) as a result of an avoided crossing with the 3 math state. The probability that some vibrational levels of this well could be populated is discussed within an approached Landau–Zerner model and is found to be high. No evidence is found of the E(4sσ) math state in the region of the “D complex”. Instead, the spectroscopic properties obtained from the (4sσ) 6 math adiabatic curve of the present work seem to agree with those of the experimental F(4pσ) math state. The FCI calculations provide benchmark results for other correlation models for the open-shell BeH system and evidence both the limitations and capabilities of the basis [email protected] [email protected]

A Time Purified Separated Antiproton Beam At The AGS

Physic

A POLARIMETER FOR PROTONS BETWEEN 100 AND 800 MeV

A carbon polarimeter has been built and used for protons with energies between 100 and 800 MeV. The polarimeter accepts scatters in the carbon analyzer up to 30~ab, with negligible instrumental asymmetries. Drift chambers 60 cm square were used with a system for resolving the left-right ambiguity inherent in drift chambers. A hardware system for rejecting small angle scatters is described. The polarimeter is routinely used to measure spin transfer parameters with a typical precision of ±0.03 in about eight hours of low-duty LAMPF beam