348 research outputs found

    Pre-Education Programs: A Comprehensive Project at Henry Ford Community College

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    Henry Ford Community College (HFCC) in Dearbom, Michigan is a two-year institution of higher education serving a diverse student population of approximately 13,000 students. In addition to providing a broad array of technical and vocational programs, the College provides the first two years of a baccalaureate program. However, the transferability of these programs is not assured. In the absence of a mandated state-wide curriculum, two- and four-year colleges and universities in Michigan develop courses and programs independently, and the transfer of courses between institutions is determined independently by the respective departments. The end result is often loss of credit when a community college student transfers. Other problems faced prospective education majors as well. Students were justifiably apprehensive about the suitability of their academic preparation for the challenges they would confront at the four-year institution. To address this and other problems, HFCC initiated a comprehensive project to develop a structured teacher education program. The project consisted of two components: 1) creation of pre-education programs and 2) institution of articulated transfer agreements as a result of collaboration with neighboring universities. The success of this reform is underscored by a dramatic increase in HFCC pre-education majors from 354 students in 1994 to 697 in 1997, with 80 students designating minority status in 1994 and 179 in 1997

    Monitoring of the accelerator beam distributions for internal target facilities

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    We describe a direct method for monitoring the geometrical dimensions of a synchrotron beam at the target position for internal target installations. The method allows for the observation of the proton beam size as well as the position of the beam relative to the target. As a first demonstration of the technique, we present results obtained by means of the COSY-11 detection system installed at the cooler synchrotron COSY. The influence of the stochastic cooling on the COSY proton beam dimensions is also investigated.Comment: 7 pages, 8 figures, Submitted to Nucl. Inst. & Meth.

    Near threshold eta meson production in dp collisions

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    Preliminary results of recent measurements of the near threshold eta meson production in the dp-->dp eta reaction are presented. The experiment was performed at the COSY-Juelich accelerator with the use of the COSY-11 detection system. Data were taken for three values of deuteron beam momenta corresponding to excess energies of 3.2, 6.1 and 9.2 MeV. The energy dependence of the total cross section confirms a strong effect of the final state interaction.Comment: Talk given at 9th International Workshop on Meson Production, Properties and Interaction, Cracow, Poland, 9-13 June 2006. 5 pages, 3 figure

    S-wave eta'-proton FSI; phenomenological analysis of near-threshold production of pi0, eta, and eta' mesons in proton-proton collisions

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    We describe a novel technique for comparing total cross sections for the reactions pp --> pp pi(0), pp --> pp eta, and pp --> pp eta' close to threshold. The initial and final state proton-proton interactions are factored out of the total cross section, and the dependence of this reduced cross section on the volume of phase space is discussed. Different models of the proton-proton interaction are compared. We argue that the scattering length of the S-wave eta'-proton interaction is of the order of 0.1 fm.Comment: 10 pages, 5 figure

    Kaon Production and Interaction

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    Exclusive data on both the elementary kaon and antikaon production channels have been taken at the cooler synchrotron COSY in proton-proton scattering. In the kaon--hyperon production an enhancement by one order of magnitude of the Lambda/Sigma0 ratio has been observed at excess energies below Q=13 MeV compared to data at higher excess energies (Q>300 MeV). New results obtained at the COSY-11 facility explore the transition region between the regime of this low-energy Sigma0 suppression and excess energies of 60 MeV. A comparison of the energy dependence of the Lambda and Sigma0 total cross sections exhibits distinct qualitative differences between both hyperon production channels. Studies of kaon-antikaon production have been motivated especially by the ongoing discussion about the nature of the scalar resonances f0(980) and a0(980) coupling to the K anti-K channel. For the reaction pp->ppK+K- a first total cross section value is reported at an excess energy of Q=17 MeV, i.e. below the phi threshold. Calculations obtained within an OBE model indicate that the energy dependence of the available total cross section data close to threshold is rather difficult to reconcile with the assumption of a phase-space behaviour modified predominantly by the proton-proton final state interaction.Comment: 10 pages, 4 figures, Presented at Meson 2002: 7th International Workshop on Meson Production, Properties and Interaction, Cracow, Poland, 24-28 May 200

    Measurement of the dp -->3He eta reaction near threshold

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    Total and differential cross sections for the dp --> 3He eta reaction have been measured near threshold for 3He center-of-mass momenta in the range from 17.1 MeV/c to 87.5 MeV/c. The data were taken during a slow ramping of the COSY internal deuteron beam scattered on a proton target detecting the 3He ejectiles with the COSY-11 facility. The forward-backward asymmetries of the differential cross sections deviate clearly from zero for center-of-mass momenta above 50 MeV/c indicating the presence of higher partial waves in the final state. Below 50 MeV/c center-of-mass momenta a fit of the final state enhancement factor to the data of the total cross sections results in the 3He eta scattering length of a = |2.9 +/- 0.6| + i (3.2 +/- 0.4) fm

    Study of the mechanism of the five-nucleon transfer reaction 12^{12}C(13^{13}C, 8^{8}Be)17^{17}O

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    Excitation functions (Ecm_{cm} = 13.4 - 16.8 MeV) and angular distributions (Ecm_{cm} = 13.8 and 16.38 MeV) of 12^{12}C(13^{13}C, 8^{8}Be)17^{17}O reaction have been measured and analysed by means of statistical and direct reaction mechanism models. The direct reaction analysis includes one and two step processes. For this purpose measurements and analyses were also performed for the reactions 12^{12}C(13^{13}C, 9^{9}Be)16^{16}O (at Ecm_{cm} = 13.8 MeV) and 16^{16}O(9^{9}Be, 8^{8}Be)17^{17}O (at Ecm_{cm} = 10.3 and 12.8 MeV). The results were used to estimate the magnitude of the direct two-step (n-4^{4}He) and (4^{4}He-n) transfers in the 12^{12}C(13^{13}C, 8^{8}Be)17^{17}O reaction. These two-step transfers as well as the compound nucleus mechanism, account only for approximately 10% of the experimental cross sections. Thus a dominance of the one-step five-nucleon transfer is concluded. Estimates of the direct 5^{5}He-cluster transfer describe the data qualitatively

    On the close to threshold meson production in neutron-neutron collisions

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    A method of measuring the close to threshold meson production in neutron-neutron collisions is described where the momenta of the colliding neutrons can be determined with the accuracy obtainable for the proton-proton reaction. The technique is based on the double quasi-free nn --> nn X^0 reaction, where deuterons are used as a source of neutronsComment: 6 pages, 2 figures, to be published in Phys. Lett.

    Compressive Sensing of Signals Generated in Plastic Scintillators in a Novel J-PET Instrument

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    The J-PET scanner, which allows for single bed imaging of the whole human body, is currently under development at the Jagiellonian University. The dis- cussed detector offers improvement of the Time of Flight (TOF) resolution due to the use of fast plastic scintillators and dedicated electronics allowing for sam- pling in the voltage domain of signals with durations of few nanoseconds. In this paper we show that recovery of the whole signal, based on only a few samples, is possible. In order to do that, we incorporate the training signals into the Tikhonov regularization framework and we perform the Principal Component Analysis decomposition, which is well known for its compaction properties. The method yields a simple closed form analytical solution that does not require iter- ative processing. Moreover, from the Bayes theory the properties of regularized solution, especially its covariance matrix, may be easily derived. This is the key to introduce and prove the formula for calculations of the signal recovery error. In this paper we show that an average recovery error is approximately inversely proportional to the number of acquired samples

    Application of the Compress Sensing Theory for Improvement of the TOF Resolution in a Novel J-PET Instrument

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    Nowadays, in Positron Emission Tomography (PET) systems, a Time of Flight information is used to improve the image reconstruction process. In Time of Flight PET (TOF-PET), fast detectors are able to measure the difference in the arrival time of the two gamma rays, with the precision enabling to shorten significantly a range along the line-of-response (LOR) where the annihilation occurred. In the new concept, called J-PET scanner, gamma rays are detected in plastic scintillators. In a single strip of J-PET system, time values are obtained by probing signals in the amplitude domain. Owing to Compress Sensing theory, information about the shape and amplitude of the signals is recovered. In this paper we demonstrate that based on the acquired signals parameters, a better signal normalization may be provided in order to improve the TOF resolution. The procedure was tested using large sample of data registered by a dedicated detection setup enabling sampling of signals with 50 ps intervals. Experimental setup provided irradiation of a chosen position in the plastic scintillator strip with annihilation gamma quanta
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