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J Alster

Publications and source records attributed to J Alster.

At least 19 recordsLinked to original sources
PubMed2003

n-p short-range correlations from (p,2p+n) measurements.

We studied the 12C(p,2p+n) reaction at beam momenta of 5.9, 8.0, and 9.0 GeV/c. For quasielastic (p,2p) events p(f), the momentum of the knocked-out proton before the reaction, was compared (event by event) with p(n), the coincident neutron momentum. For |p(n)|>k(F)=0.220 GeV/c (the Fermi momentum) a strong back-to-back directional correlation between p(f) and p(n) was observed, indicative of short-range n-p correlations. From p(n) and p(f) we constructed the distributions of c.m. and relative motion in the longitudinal direction for correlated pairs. We also determined that 49+/-13% of events with |p(f)|>k(F) had directionally correlated neutrons with |p(n)|>k(F).

Journal Article↗
PubMed2001

Energy dependence of nuclear transparency in C (p,2p) scattering.

The transparency of carbon for (p,2p) quasielastic events was measured at beam momenta ranging from 5.9 to 14.5 GeV/c at 90 degrees c.m. The four-momentum transfer squared (Q2) ranged from 4.7 to 12.7 (GeV/c)(2). We present the observed beam momentum dependence of the ratio of the carbon to hydrogen cross sections. We also apply a model for the nuclear momentum distribution of carbon to obtain the nuclear transparency. We find a sharp rise in transparency as the beam momentum is increased to 9 GeV/c and a reduction to approximately the Glauber level at higher energies.

Journal Article↗
PubMed1995

Psychological profile of help-seeking and non-help-seeking tinnitus patients.

The psychological profile of tinnitus patients who sought treatment (Help-Seeking, HS) was compared with that of patients who did not seek help (non-help-seeking, NHS) and with normal control subjects. Psychological evaluations as well as hearing, tinnitus loudness, and tinnitus pitch were measured. Overall, the psychiatric symptomatology of HS (n = 50) was more severe with poorer effective coping abilities and externalization of locus of control than NHS (n - 50). However, the psychiatric symptomatology of the NHS was remarkably more severe than that in the normals (n = 73) and more like that in the HS even though they did not turn to treatment. Tinnitus loudness was significantly lower in HS than in NHS subjects. The lower the tinnitus loudness, the higher the psychiatric symptomatology. The trend towards subclinical abnormalities in NHS indicates their vulnerability to pathology and this requires the attention of the therapist in order to increase the patient's self-awareness and to suggest preventive coping strategies or relaxation techniques.

Adaptation, Psychological↗
PubMed1990

Structure of 1,4-cubanediyldiammonium bis(trinitromethanide).

C8H12N2+.2CN3O6-, Mr = 436.27, monoclinic, C2/m, a = 14.298 (2), b = 8.408 (1), c = 7.354 (2) A, beta = 103.42 (2) degrees, V = 859.9 (5) A3, Z = 2, Dx = 1.68 g cm-3, lambda(Mo K alpha) = 0.71069 A (graphite monochromator), mu = 1.66 cm-1, F(000) = 448, T = 293 K, final R = 0.039 for 672 reflections with I greater than or equal to 3 sigma(I). The cubanediyldiammonium cation and trinitromethanide anion have 2/m and m crystallographic symmetries, respectively. The cation is linked to six trinitromethanide anions, three at each end, by a total of 12 N--H...O hydrogen bonds through the six cation H atoms. The cubane cage has a local threefold axis of symmetry along the long axis (N1...N1) of the cation and undergoes a large librational motion, 17 degrees r.m.s. amplitude, about this axis.

Bridged-Ring Compounds↗