Top PDF Capture Cross Section of C^(13) for Low Energy Protons

Capture Cross Section of C^(13) for Low Energy Protons

Capture Cross Section of C^(13) for Low Energy Protons

The cross section for this reaction was estimated to be 4 x lo-33 cm2 at 130 kilovolts bombarding energy and even with the increased detector efficiency obtained through the use of a sci[r]

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Measurement of the radiative capture cross section of the s-process branching points 204Tl and 171Tm at the n-TOF facility (CERN)

Measurement of the radiative capture cross section of the s-process branching points 204Tl and 171Tm at the n-TOF facility (CERN)

The nucleosynthesis of elements heavier than iron in the Universe is mainly produced by a series of neutron capture reactions and beta-decays in the so-called slow (s) and rapid (r) processes. The main features and basic characteristics of both processes were already well sketched in the seminal papers by Burbidge et al. [1] and Cameron [2]. An up to date review of the s-process, including the main stellar sites where it takes place, can be found in Käppeler et al. [3].The s-process mechanism operates during core He-burning and shell C-burning in massive stars of M>8M sun (also called weak s-process), as well as in H-burning and He-
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Measurement of the radiative capture cross section of the s-process branching points 204Tl and 171Tm at the n_TOF facility (CERN)

Measurement of the radiative capture cross section of the s-process branching points 204Tl and 171Tm at the n_TOF facility (CERN)

The nucleosynthesis of elements heavier than iron in the Universe is mainly produced by a series of neutron capture reactions and beta-decays in the so-called slow (s) and rapid (r) processes. The main features and basic characteristics of both processes were already well sketched in the seminal papers by Burbidge et al. [1] and Cameron [2]. An up to date review of the s-process, including the main stellar sites where it takes place, can be found in Käppeler et al. [3].The s-process mechanism operates during core He-burning and shell C-burning in massive stars of M>8M sun (also called weak s-process), as well as in H-burning and He-
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Preliminary results on the 233U capture cross section and alpha ratio measured at n_TOF (CERN) with the fission tagging technique

Preliminary results on the 233U capture cross section and alpha ratio measured at n_TOF (CERN) with the fission tagging technique

A previous experiment [11] at n_TOF using MicroMegas (MGAS) detectors as fission detector showed that the copper mesh of the MicroMegas is a significant source of background for neutron energies above 100 eV. Thus, a novel fission detector was designed, see Fig. 5, respecting the main constraints namely a) the restricted space inside the absorber of the TAC (maximum diameter of 10 cm); b) the fast response needed to reduce pile-up due to the high α-activity of the 233 U targets; c) the hosting of the maximum number of 233 U

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The Gogny-HFB+QRPA dipole strength function and its application to radiative neutron capture cross section

The Gogny-HFB+QRPA dipole strength function and its application to radiative neutron capture cross section

Abstract. Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the E1 and M1 absorption γ-ray strength function obtained in the framework of the axially- symmetric deformed quasiparticle random phase approximation (QRPA) based on the finite-range D1M Gogny force to the determination of the de-excitation strength function. To do so, shell-model calculations of the de-excitation dipole strength function as well as experimental data are considered to provide insight in the low-energy limit and to complement the QRPA estimate phenomenologically. We compare our final prediction of the E1 and M1 strengths with available experimental data at low energies and show that a relatively good agreement can be obtained. Its impact on the average radiative width as well as radiative neutron capture cross section is discussed.
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Relative Differential Cross Section Measurements in H+- CO2 Low Energy Collisions

Relative Differential Cross Section Measurements in H+- CO2 Low Energy Collisions

Ions are generated in the Colutron ion source that was operated at 180 mTorr with a mixture of 80/100 argon to hydrogen with typical filament current of 0.1 A, and anode voltage of 80 volts. Ions within 1 to 10 keV of energy were directed into the Wien velocity filter (both Colutron source and Wien filter not shown in figure 1). The protons were selected and allowed into a 10 degrees deflection angle in order to remove neutrals. Following that, they were allowed to pass through two sets of collimators of 1 and 2 mm diameters into the interaction region. The interaction of protons with target gas occurs under the end of a hypodermic needle jet of 0.1 mm diameter. The gas pressure is measured in the surrounding of the jet region. The proton beam and the resulting neutrals are monitored and measured downstream with a Faraday cup and a channeltron.
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Antiproton-nucleus annihilation cross section at low energy

Antiproton-nucleus annihilation cross section at low energy

Abstract. The antinucleon-nuclei annihilation cross sections at low energies were sys- tematically measured at CERN in the 80’s and 90’s with the LEAR facility and later with the Antiproton Decelerator. Unfortunately only few data exist for very low energy antiprotons (p<500 MeV/c) on medium and heavy nuclei. A deeper knowledge is re- quired by fundamental physics and can have consequence also in cosmology and medical physics. In order to fill the gap, the ASACUSA Collaboration has very recently measured the annihilation cross section of 100 MeV/c antiprotons on carbon. In the present work the experimental result is presented together with a comparison both with the antineutron data on the same target at the same energies and with the other existing antiproton data at higher energies.
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Measurement of the differences in the total cross section for antiparallel and parallel longitudinal spins and a measurement of parity nonconservation with incident polarized protons and antiprotons at 200 GeV/c

Measurement of the differences in the total cross section for antiparallel and parallel longitudinal spins and a measurement of parity nonconservation with incident polarized protons and antiprotons at 200 GeV/c

multiperipheral model @ 73 # , and heavy-boson exchange @ 74 # . At higher energies, a quark-model calculation @ 75,76 # of A L shows that the dominant contribution comes from the parity-nonconserving interaction of two quarks from the same beam proton that may be described as a mixing of the beam protons into intermediate states of negative parity. This higher-twist subprocess dominating the high-energy asym- metry can be approximated in the parton model as quark- vector diquark scattering. A vector diquark from the polar- ized proton ~ unpolarized target ! interacts strongly with a quark from the unpolarized target ~ polarized beam ! with the parity-nonconserving weak interaction occurring only be- tween the quarks of the vector diquark. The asymmetry con- tains soft processes with poorly-known individual param- eters, so the normalization needs to be fixed by experimental data. Once this is fixed, all of the uncertainty in the asym- metry is due to a parameter b, which effectively represents the rate of scale variation of the strength of the QCD cou- pling. By fixing the normalization to the 5.1-GeV data point, the theoretical prediction at 800 MeV matches the experi- mental value fairly well. This calculation predicts a value of A L ; 10 2 4 at a laboratory momentum of 200 GeV/c for
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Capture cross sections on unstable nuclei

Capture cross sections on unstable nuclei

The calculation of the E1-strength function necessi- tates the knowledge of the low-energy tail of the GDR, governed by the ( γ, γ ) cross section below the neutron separation energy [2]. Figure 1 shows the main modes of excitations which take place below the GDR. As can be seen, the Pygmy Dipole Resonance (PDR) defines a specific relief of the nuclear dipole response at the tail of the GDR. Measurements at the High Intensity Gamma- Ray Source (HIγ S) facility using monoenergetic and 100% polarized photon beams confirmed the theoretical predictions that the PDR is dominated by E1 excitations [3,4]. Recent experimental and advanced microscopic theoretical studies of the low-energy dipole response of N = 82 and N = 50 isotopes indicate the existence of M1 dipole strength below and closely above the neutron threshold which is related to the excitation of the isovector spin-flip giant resonance [4,5]. However, the determination of neutron-capture reaction rates is based on ‘pure’ statistical HF codes which do not account for M1 contributions. Furthermore, higher-order multipole admixtures e.g., E2 strengths, should be also included to the total photon-transmission coefficient, even though they are expected to have a minuscule amount of the total γ SF.
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Optimization of Energy Density in Girders under Pure Bending with an Extruded Monolithic Cross Section

Optimization of Energy Density in Girders under Pure Bending with an Extruded Monolithic Cross Section

Traditionally, girders subjected to pure bending have been optimized based on either the material or the geometry of the resistant cross-section. Normally, the resistant cross-section in IPN/UPN sections or in sandwich panels is optimized. In regard to the materials, unidirectional compound materials in which the al- lowable compression stress is approximately half the allowable tensile stress may be used. This type of material may be used in pure bending, but use in combined load states may cause shear issues and loss of properties in the fiber’s transversal length. In regard to the resistant cross-section, different studies have been done on the influence of the type of cross-section with design criteria such as the re- sistance or energy storage.
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Measurements of the proton-air cross section with high energy cosmic ray experiments

Measurements of the proton-air cross section with high energy cosmic ray experiments

The high energy models used to determine the value of K are QGSJETII.4 [6], QGSJET01 [7], SIBYLL [8], and EPOS-LHC [9]. Several data sets of air showers in the energy range of 10 18.3 -10 19.3 eV were simulated using each of the above models. K is found to be fairly constant between the energies of 10 18.3 -10 19.3 eV, for each of the high energy models [10]. This finding justifies the use of a single average value over the range of interest. Table 1 summarizes each of the high energy models used, the corresponding value of K and consequently σ inel

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Photo Ionization Cross Section and Binding Energy of Exciton in a Parabolic Quantum Well

Photo Ionization Cross Section and Binding Energy of Exciton in a Parabolic Quantum Well

for a barrier heights corresponding to the Al composition x=0.3. The barrier heights of conduction band and valence band are calculated as 246.87 and 132.93 meV respectively. When L is increases, the binding energy also increases for both heavy and light hole exciton due to the compression of exciton wave function in the quantum well. If the L is increases further, binding energy reach a maximum value and then start to decrease rapidly due to spread out of the wave-function into the barrier of the well. It is also noted that the binding energy of heavy hole exciton is more bound compare the light hole exciton due to . The peak value of binding for heavy hole exciton is observed at L = 43nm. Similarly the peak value of binding energy for light hole exciton is observed at L = 42nm. This behavior is the similar to the cases of a hydrogenic donor in potential wells of varied profiles [3, 4, 5, 7, 18, 20].
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Energy Consumption and Economic Growth Revisited: Structural Breaks and Cross-section Dependence

Energy Consumption and Economic Growth Revisited: Structural Breaks and Cross-section Dependence

Lee (2005) examined 18 developing countries over the period 1975-2001. He found uni- directional causality running from energy consumption to growth. This finding suggests that energy conservation may harm economic growth in developing countries. In contrast, Al-Iriani (2006) found uni-directional causality running from growth to energy consump- tion for six member countries of the Gulf Cooperation Council (GCC) covering the period 1971-2002. Thus, energy conservation policies may be adopted by the GCC without any adverse effects on economic growth. Correspondingly, the panel data studies listed in Table 1 in general provide ambiguous empirical results on the energy consumption-growth nexus similar to that found in time series studies. Even the distinction between developed and developing countries leads to no clear evidence for either group of countries. Similar to Lee (2005) and Al-Iriani (2006), most panel data analyses have applied the panel unit root tests proposed by Hadri (2000), Levin et al. (2002) (LLC) and/or Im et al. (2003) (IPS), the Pedroni (1999, 2004) panel cointegration test and the panel generalised method of moments (GMM) estimator proposed by Arellano and Bond (1991) to test for panel Granger causality. Furthermore, the listed studies also often use the Breitung (2000), and the Fisher-type ADF and PP tests (see Choi, 2001; Maddala and Wu, 1999) to test for unit roots. In addition, the long-run relationship between energy consumption and GDP, which is commonly confirmed by means of the already mentioned Pedroni (1999, 2004) test, is almost always estimated with fully modified OLS (FMOLS) as suggested in Pedroni (2000). In view of the repeated application of the same methods that continue to provide conflicting evidence, even for pan- els of similar countries, further methodological improvements seem to be necessary.
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Radiative capture of photons by C^(12) and C^(13)

Radiative capture of photons by C^(12) and C^(13)

Laboratory, and for suggesting and encouragin g this investi gation. I gratefully acknowledge discussion of the results with Professors R. Perry for his further corre[r]

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A Theoretical Study of Stopping Power and Range For Low Energy (<3.0mev) Protons In Aluminium, Germanium, Lead, Gold and Copper Solid Materials

A Theoretical Study of Stopping Power and Range For Low Energy (<3.0mev) Protons In Aluminium, Germanium, Lead, Gold and Copper Solid Materials

The range is the mean path length a charged particle travels in target matter before coming to rest. When a proton enters into a medium it immediately interacts simultaneously with many electrons. In any one encounter the electron feels an impulse from the attractive coulomb forces as the particle passes its vicinity. This impulse may be sufficient either to raise the electron to a higher level shell within the target atom (excitation) or to remove completely the electron from the atom (ionization). The energy that is transferred to the electron come at the expense of the charged particle, and its velocity is therefore, decreased as a result of inelastic collision. The maximum energy that can be transferred from a charged particle of mass, m with kinetic energy, E to an electron of mass, m e in a single collision is given by the expression;
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The role of DSM + C to facilitate the integration of renewable energy and low carbon energy technologies

The role of DSM + C to facilitate the integration of renewable energy and low carbon energy technologies

The impact for low level demand profile (such as physically-based demand models) can be quantified through calculating the relevant micro-environmental parameters within the demand models. It can decide the control action by comparing the new values of control variables with the initial settings whether the customer minimum comfort levels are violated. Through this way, the CD parameter can be quantified automatically. Discrepancies between real effects on the load demand curve and preliminary results are mainly due to the incorrect modeling of loads involved in these control strategies (Molina et al, 2003). Therefore the more accuracy the demand model is, the more realistic load control strategy provides. At this stage for the SuperGen project, the physically-based demand model for cooling and heating system is developed for the purpose of low level load control algorithm application. Physically based load modeling methodologies have been widely used, because they are able to predict the individual load dynamic response and allow one to obtain the aggregated response of these loads efficiently.
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Research on Minimum Energy Excited to Plasma Coating for Reducing Radar Cross Section of Target

Research on Minimum Energy Excited to Plasma Coating for Reducing Radar Cross Section of Target

Abstract—To reduce the radar cross section (RCS) of a target, plasma coating on perfectly electric conducting plate is studied in this paper. Nonuniform helium plasma produced by a minitype solid rocket engine is with collisional and unmagnetized. Energy excited for generating helium plasma is investigated. Based on the collisional, unmagnetized, and cold plasma model, backscattering RCS is computed by using finite-difference time-domain method. Principle of RCS reduction is explained. To find minimum input energy while RCS reduced, relationship between input power and RCS reduction is discussed, and numerical optimization is also implemented. We can identify optimal parameters and choose the best electron density profile under condition of given input power level.
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& Tunnel Cross Section

& Tunnel Cross Section

17 October 2007 20.. Civil Engineering Layouts & Tunnel Cross Section. TS Department / Civil Engineering Group[r]

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Section Energy Efficiency

Section Energy Efficiency

bridging within the building envelope, which occurs when building elements conduct more heat than the insulated portion of the building envelope, which can lead to significant heat loss through the thermal bridge. The most typical case to which Clause 9.36.2.5.(2)(a) applies is that of a firewall that must completely penetrate the building envelope (see Figure A-9.36.2.5.(2)-A). Figures A-9.36.2.5.(2)-B and A-9.36.2.5.(2)-C illustrate the insulation options presented in Clauses 9.36.2.5.(2)(b) and (c).

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Cross sections of nuclear isomers from the interaction of protons with the thin thorium target

Cross sections of nuclear isomers from the interaction of protons with the thin thorium target

The samples, using a special device, were placed in the ac- celerator chamber at a radius corresponding to the energy of pro- tons 100 and 600 MeV at the current of 0.3 µA. The position of the 100 and 600 MeV beams was determined by placing an alu- minum foil inside the accelerator and perpendicular to the pro- ton beam and evaluating the activity of the foil. For the target, foils of 232 Th were used with a thickness of 100 microns and a weight of 149.5 mg placed between two Al foils with thickness of 50mkm. The foil area was 1.5 cm 2 . The target was placed in such way that the proton beam was hitting the edge of the target as it shows on Fig. 2. The dimensions of the beam in the cross section were ∆ X = 2.5 cm and ∆ Y = 2.6 cm. To determine the integral flow of protons falling on the 232 Th samples, an activa-
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