We present a search at the Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling α' to electrons. Such a particle A' can be produced in electron-nucleus ...fixed-target scattering and then decay to an e + e- pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175-250 MeV, found no evidence for an A'→ e+ e- reaction, and set an upper limit of α'/α ~/= 10(-6). Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.
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The experiment E94-107 in Hall A at Jefferson Lab started a systematic study of high-resolution hypernuclear spectroscopy in the 0p-shell region of nuclei such as the hypernuclei produced in ...electroproduction on Be-9, C-12, and O-16 targets. In order to increase counting rates and provide unambiguous kaon identification, two superconducting septum magnets and a ring-imaging Cherenkov detector were added to the Hall A standard equipment. The high-quality beam, the good spectrometers, and the new experimental devices allowed us to obtain very good results. For the first time, measurable strength with sub-MeV energy resolution was observed for the core-excited states of B-12(Lambda). A high-quality N-16(Lambda) hypernuclear spectrum was likewise obtained. A first measurement of the Lambda binding energy for N-16(Lambda), calibrated against the elementary reaction on hydrogen, was obtained with high precision, 13.76 +/- 0.16 MeV. Similarly, the first Li-9(Lambda) hypernuclear spectrum shows general agreement with theory (distorted-wave impulse approximation with the SLA and BS3 electroproduction models and shell-model wave functions). Some disagreement exists with respect to the relative strength of the states making up the first multiplet. A Lambda separation energy of 8.36 MeV was obtained, in agreement with previous results. It has been shown that the electroproduction of hypernuclei can provide information complementary to that obtained with hadronic probes and the gamma-ray spectroscopy technique.
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The experiment E94-107 in Hall A at Jefferson Lab started a systematic study of high-resolution hypernuclear spectroscopy in the 0p-shell region of nuclei such as the hypernuclei produced in ...electroproduction on Be-9, C-12, and O-16 targets. In order to increase counting rates and provide unambiguous kaon identification, two superconducting septum magnets and a ring-imaging Cherenkov detector were added to the Hall A standard equipment. The high-quality beam, the good spectrometers, and the new experimental devices allowed us to obtain very good results. For the first time, measurable strength with sub-MeV energy resolution was observed for the core-excited states of B-12(Lambda). A high-quality N-16(Lambda) hypernuclear spectrum was likewise obtained. A first measurement of the Lambda binding energy for N-16(Lambda), calibrated against the elementary reaction on hydrogen, was obtained with high precision, 13.76 +/- 0.16 MeV. Similarly, the first Li-9(Lambda) hypernuclear spectrum shows general agreement with theory (distorted-wave impulse approximation with the SLA and BS3 electroproduction models and shell-model wave functions). Some disagreement exists with respect to the relative strength of the states making up the first multiplet. A Lambda separation energy of 8.36 MeV was obtained, in agreement with previous results. It has been shown that the electroproduction of hypernuclei can provide information complementary to that obtained with hadronic probes and the gamma-ray spectroscopy technique.
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The charge and magnetic form factors, F-C and F-M, respectively, of He-3 are extracted in the kinematic range 25 fm(-2) <= Q(2) <= 61 fm(-2) from elastic electron scattering by detecting He-3 recoil ...nuclei and scattered electrons in coincidence with the two High Resolution Spectrometers of the Hall A Facility at Jefferson Lab. The measurements find evidence for the existence of a second diffraction minimum for the magnetic form factor at Q(2) = 49.3 fm(-2) and for the charge form factor at Q(2) = 62.0 fm(-2). Both minima are predicted to exist in the Q(2) range accessible by this Jefferson Lab experiment. The data are in qualitative agreement with theoretical calculations based on realistic interactions and accurate methods to solve the three-body nuclear problem
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The extent to which older workers leave their jobs rather than adapt to workplace changes has a significant effect on the organizations they work for, on government programs, especially Social ...Security, and on the workers themselves. Conceptualizing the work adaptation process begins by recognizing that older employees have needs, values, and interests that must be met by their jobs for them to choose to remain employed and adapt to workplace changes. Simultaneously, a job has knowledge, skill, and ability requirements that must be met by an older employee for the employer to choose to retain him or her. As a job changes, the individual job fit is also likely to change, often with the result that the employee is required to adapt. A review of the literature shows that there are a variety of factors at the individual, organizational, and environmental levels that affect an older worker's ability and choice to adjust to workplace changes. These factors include, for example, training throughout an individual's career, personnel policies affecting older workers, and age discrimination. This article reviews the literature describing the conceptual framework and major individual and organizational factors found to affect an older worker's ability and choice to adapt to workplace changes.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Identifies and describes strategies used throughout Texas for overcoming barriers to service use among low-income minority elderly persons. Describes strategies addressing lack of knowledge (use of ...influential groups, working with significant individuals, media use), lack of access (transportation, affordability, availability), and lack of intent (cultural differences, making services attractive, and overcoming negative attitudes toward service use). (Author/NB)
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