Covered Energy Range Research Articles

3He(α,γ)7Be cross section measurement around7Be known energy levels

The3He(α,γ)7Be reaction plays an important role in two astrophysical scenarios. It is a key reaction in lithium production during the Big Bang Nucleosynthesis and one of the central reaction in the p-p chain in stars. In the case of the former event, the Gamow energy of the reaction is around 0.2 MeV, while in the case of the p-p chain in the Sun, an order of magnitude less, around 0.023 MeV. Experimental investigation at such low energies is very difficult, if possible at all, thus low energy extrapolation inevitable to predict the reaction rate at these energies. The extrapolation and its uncertainty are influenced by the precision and covered energy range of the data used. There are many precision datasets between Ec.m.= 0.3–3.1 MeV, but only one below and one above. At higher energies known levels of7Be exist, which motivates the study of that energy range. Therefore, we performed investigations in the energy range of Ec.m.= 4.3–8.3 MeV, where the radiative cross section has not been studied so far. For the cross section determination, the activation technique was used utilising a thin-windowed gas cell and the MGC-20 cyclotron of ATOMKI.

A DuMond-type crystal spectrometer for synchrotron-based X-ray emission studies in the energy range of 15-26 keV.

The design and performance of a high-resolution transmission-type X-ray spectrometer for use in the 15-26 keV energy range at synchrotron light sources is reported. Monte Carlo X-ray-tracing simulations were performed to optimize the performance of the transmission-type spectrometer, based on the DuMond geometry, for use at the Super X-ray absorption beamline of the Swiss Light Source at the Paul Scherrer Institute. This spectrometer provides an instrumental energy resolution of 3.5 eV for X-ray emission lines around 16 keV and 12.5 eV for emission lines at 26 keV, which is comparable to the natural linewidths of the K and L X-ray transitions in the covered energy range. First experimental data are presented and compared with results of the Monte Carlo X-ray simulations.

New experimental stopping power data of 4He, 16O, 40Ar, 48Ca and 84Kr projectiles in different solid materials

Abstract New experimental data on energy loss of 4 He, 16 O, 40 Ar, 48 Ca and 84 Kr ions in thin, self-supporting foils of C, Al, Ni, Ag, Lu, Au, Pb and Th are presented. The measurements, using the TOF-E method, were done in a very broad energy range around the stopping power maximum; typically from 0.1 to 11 MeV/u. When available, the extracted stopping power values are compared with the previously published data. The overall agreement is good although a fair comparison is difficult as the covered energy range is much larger than in previous measurements. The small error bars and a broad coverage allowed us to test the predictions of theoretical codes: PASS, CasP, and semi-empirical programs: SRIM, LET, MSTAR, and the Hubert table predictions. The deviations of PASS predictions from the experimental data do not exceed 20% for all the measured combinations. CasP predictions are within 15% from the data for heavier ions but diverge up to 40% for lighter ions. Semi-empirical approaches, including SRIM, deviate from the experimental data by less than 5% for the regions already covered by previous experiments but err by about 10–20% for the ion/target combinations that were not measured before: Ca in Lu as well as Kr in Lu, Pb, and Th.

Inferences on mass composition and tests of hadronic interactions from 0.3 to 100 EeV using the water-Cherenkov detectors of the Pierre Auger Observatory

We present a new method for probing the hadronic interaction models at ultrahigh energy and extracting details about mass composition. This is done using the time profiles of the signals recorded with the water-Cherenkov detectors of the Pierre Auger Observatory. The profiles arise from a mix of the muon and electromagnetic components of air showers. Using the risetimes of the recorded signals, we define a new parameter, which we use to compare our observations with predictions from simulations. We find, first, inconsistencies between our data and predictions over a greater energy range and with substantially more events than in previous studies. Second, by calibrating the new parameter with fluorescence measurements from observations made at the Auger Observatory, we can infer the depth of shower maximum Xmax for a sample of over 81,000 events extending from 0.3 to over 100 EeV. Above 30 EeV, the sample is nearly 14 times larger than what is currently available from fluorescence measurements and extending the covered energy range by half a decade. The energy dependence of ?Xmaxcopyright is compared to simulations and interpreted in terms of the mean of the logarithmic mass. We find good agreement with previous work and extend the measurement of the mean depth of shower maximum to greater energies than before, reducing significantly the statistical uncertainty associated with the inferences about mass composition.

Dielectric-function analysis of metals for plasmonic-device application

We study the potential of various metals (Pt, Al, Cu and Ni) as plasmonic material used for devices by analyzing their complex permittivity and comparing with other metals. Metals were characterized by using high-resolution spectroscopic ellipsometry covering energy range of 0.5 to 6.5 eV. In fitting process, instead using Drude model, we used the combination of Lorentz model to describe optical properties of metals. The results show that each metal has unique different features of ε1 and ε2 in range of far-infrared to vacuum-ultraviolet. Also, the loss by interband transition is observable for some metals. Furthermore, the plasmonic quality-factor, which are related to electric-field enhancement and heat production generated by surface plasmon, of metal nanoparticle have been calculated and we found the optimum region of device application for each metal. From this study, Cu is promising metal working in near-infrared to visible area potentially to substitute noble Ag and Au. On the other hand, Al is the best metal to be applied as plasmonic device working in ultraviolet region. Moreover, enhancement of plasmonic quality-factor by changing geometry and environment of metal is also discussed. Our studies give an alternative of fundamental perspective for plasmonic-device development especially for energy-harvesting purposes.

Energy loss and straggling of MeV Si ions in gases

We present measurements of energy loss and straggling of Si ions in gases. An energy range from 0.5 to 12MeV/u was covered using the 6MV EN tandem accelerator at ETH Zurich, Switzerland, and the K130 cyclotron accelerator facility at the University of Jyväskylä, Finland. Our energy-loss data compare well with calculation based on the SRIM and PASS code. The new straggling measurements support a pronounced peak in He gas at around 4MeV/u predicted by recent theoretical calculations. The straggling curve structure in the other gases (N2, Ne, Ar, Kr) is relatively flat in the covered energy range. Although there is a general agreement between the straggling data and the theoretical calculations, the experimental uncertainties are too large to confirm or exclude the predicted weak multi-peak structure in the energy-loss straggling.

First measurement of the polarization observable E in the [formula omitted] reaction up to 2.25 GeV

First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction γ→p→→π+n, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility. These polarization data agree fairly well with previous partial-wave analyses at low photon energies. Over much of the covered energy range, however, significant deviations are observed, particularly in the high-energy region where high-L multipoles contribute. The data have been included in new multipole analyses resulting in updated nucleon resonance parameters. We report updated fits from the Bonn–Gatchina, Jülich–Bonn, and SAID groups.

Real-Time Processing System for the JET Hard X-Ray and Gamma-Ray Profile Monitor Enhancement

The Joint European Torus (JET) is currently undertaking an enhancement program, in which one of the objectives is to test relevant diagnostics for the International Thermonuclear Experimental Reactor (ITER), the reference for the next generation of fusion experiments. One of the challenges in ITER is the provision of real-time data analysis and compression capabilities, to sustain the expected long duration discharges and the high acquisition rates achieved by recent data acquisition systems. Foreseeing this real-time requirement, a new system was developed and installed at JET for the gamma-ray and hard X-ray profile monitor diagnostic. The new system, which is connected to 19 CsI(Tl) photodiodes in order to obtain the line-integrated profiles of the gamma-ray and hard X-ray emissions, was designed to overcome the data acquisition limitations of the present fast electron Bremsstrahlung diagnostic (FEB), while exploiting the required real-time features. This paper presents the real-time processing architecture for the JET gamma-ray and hard X-ray profile monitor. The system hardware, based on the Advanced Telecommunication Computer Architecture (ATCA) standard, includes reconfigurable digitizer modules with embedded Field Programmable Gate Array (FPGA) devices capable of acquiring and simultaneously processing data in real-time from the 19 detectors. A suitable algorithm was developed and implemented in the FPGAs, which are able to deliver the corresponding energy of the acquired pulses, and its associated occurrence time. The real-time processed data is sent periodically, during the discharge, through the JET real-time Asynchronous Transfer Mode (ATM) network, and stored in the JET scientific databases at the end of the pulse. Publishing the processed data in the ATM network enables it to be used for machine control purposes (e.g. the information about the line-integrated emissions of the hard X-rays in real time can be used to determine the lower hybrid current drive deposition before the main heating phase). Additionally, the real-time processed data is used for local calibration, using embedded radioactive sources to build in real-time the 19 channels spectra. The acquired raw data is also stored in the digitizer modules' local memory and retrieved after the pulse to the JET database, where it can be post-processed offline to validate the real-time algorithms. The interface between the ATCA digitizers, the JET Control and Data Acquisition System (CODAS) and the JET real-time network is provided by the Multithreaded Application Real-Time executor (MARTe). From the experimental results it was concluded that it is possible to measure in real-time the line-integrals of both hard X-ray and gamma-ray emissions, covering energy range from ∼200 keV to 8 MeV. This allows us to meet two of the major milestones: the ability to process and supply high volume data rates in real-time over a wide spectrum energy range.

KASCADE-Grande measurements of energy spectra for elemental groups of cosmic rays

The KASCADE-Grande air shower experiment [1] consists of, among others, a large scintillator array for measurements of charged particles, Nch, and of an array of shielded scintillation counters used for muon counting, Nμ. KASCADE-Grande is optimized for cosmic ray measurements in the energy range 10PeV to about 2000PeV, where exploring the composition is of fundamental importance for understanding the transition from galactic to extragalactic origin of cosmic rays. Following earlier studies of the all-particle and the elemental spectra reconstructed in the knee energy range from KASCADE data [2], we have now extended these measurements to beyond 200PeV. By analysing the two-dimensional shower size spectrum Nch vs. Nμ for nearly vertical events, we reconstruct the energy spectra of different mass groups by means of unfolding methods over an energy range where the detector is fully efficient. The procedure and its results, which are derived based on the hadronic interaction model QGSJET-II-02 and which yield a strong indication for a dominance of heavy mass groups in the covered energy range and for a knee-like structure in the iron spectrum at around 80PeV, are presented. This confirms and further refines the results obtained by other analyses of KASCADE-Grande data, which already gave evidence for a knee-like structure in the heavy component of cosmic rays at about 80PeV [3].

Measurement of the reaction17O(α,n)20Ne and its impact on thesprocess in massive stars

The ratio between the rates of the reactions O-17(\alpha,n)Ne-20 and O-17(\alpha,\gamma)Ne-21 determines whether O-16 is an efficient neutron poison for the s process in massive stars, or if most of the neutrons captured by O-16(n,\gamma) are recycled into the stellar environment. This ratio is of particular relevance to constrain the s process yields of fast rotating massive stars at low metallicity. Recent results on the (\alpha,\gamma) channel have made it necessary to measure the (\alpha,n) reaction more precisely and investigate the effect of the new data on s process nucleosynthesis in massive stars. We present a new measurement of the O-17(\alpha, n) reaction using a moderating neutron detector. In addition, the (\alpha, n_1) channel has been measured independently by observation of the characteristic 1633 keV \gamma-transition in Ne-20. The reaction cross section was determined with a simultaneous R-matrix fit to both channels. (\alpha,n) and (\alpha, \gamma) resonance strengths of states lying below the covered energy range were estimated using their known properties from the literature. A new O-17(\alpha,n) reaction rate was deduced for the temperature range 0.1 GK to 10 GK. It was found that in He burning conditions the (\alpha,\gamma) channel is strong enough to compete with the neutron channel. This leads to a less efficient neutron recycling compared to a previous suggestion of a very weak (\alpha,\gamma) channel. S process calculations using our rates confirm that massive rotating stars do play a significant role in the production of elements up to Sr, but they strongly reduce the s process contribution to heavier elements.

P.3.b.003 Characterization of [3H]-LY508869 – a novel selective metabotropic glutamate 2 positive allosteric potentiator ligand

First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction γ→p→→π+n, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility. These polarization data agree fairly well with previous partial-wave analyses at low photon energies. Over much of the covered energy range, however, significant deviations are observed, particularly in the high-energy region where high-L multipoles contribute. The data have been included in new multipole analyses resulting in updated nucleon resonance parameters. We report updated fits from the Bonn–Gatchina, Jülich–Bonn, and SAID groups.

HiSCORE: A new detector for astroparticle and particle physics beyond 10 TeV

The new large-area (100km2) wide-angle (0.9sr) air Cherenkov detector HiSCORE (Hundred ⁎ i Square-km Cosmic ORigin Explorer) aims at the exploration of the cosmic ray and γ-ray sky (accelerator sky) in the so far poorly covered energy range from 10TeV to 1EeV.The main motivation for observations in this energy regime is to solve the origin of Galactic cosmic rays. Other questions of astroparticle and particle physics can be addressed in this energy regime. Furthermore, new physics questions might arise by opening the last remaining observation window of γ-ray astronomy (TeV/PeV).HiSCORE is based on non-imaging Cherenkov light-front sampling with sensitive large-area detector modules of the order of 0.5m2. Sampling the lateral photon density and arrival-time distribution allows the reconstruction of the direction, the energy and the type (mainly via the shower depth) of the primary particle.

THE HIGH-ENERGY EMISSION OF THE CRAB NEBULA FROM 20 keV TO 6 MeV WITHINTEGRALSPI

The SPI spectrometer aboard the International Gamma-Ray Astrophysics Laboratory mission regularly observes the Crab Nebula since 2003. We report on observations distributed over 5.5 years and investigate the variability of the intensity and spectral shape of this remarkable source in the hard X-rays domain up to a few MeV. While single power-law models give a good description in the X-ray domain (mean photon index ∼ 2.05) and MeV domain (photon index ∼ 2.23), crucial information is contained in the evolution of the slope with energy between these two values. This study has been carried out through individual observations and long duration (∼ 400 ks) averaged spectra. The stability of the emission is remarkable and excludes a single power-law model. The slopes measured below and above 100 keV agree perfectly with the last values reported in the X-ray and MeV regions, respectively, but without indication of a localized break point. This suggests a gradual softening in the emission around 100 keV and thus a continuous evolution rather than an actual change in the mechanism parameters. In the MeV region, no significant deviation from the proposed power-law model is visible up to 5–6 MeV. Finally, we take advantage of the spectroscopic capability of the instrument to seek for previously reported spectral features in the covered energy range with negative results for any significant cyclotron or annihilation emission on 400 ks timescales. Beyond the scientific results, the performance and reliability of the SPI instrument is explicitly demonstrated, with some details about the most appropriate analysis method.

Recent results on few-nucleon systems: Investigation from VBLHE-JINR

Recent results on the spin effects in deuteron inclusive breakup and deuteron-proton elastic scattering obtained at the Veksler and Baldin Laboratory of High Energies at JINR are reported. The experimental data have been obtained with the use of a high-energy polarized deuteron beam at the Synchrophasotron-Nuclotron Accelerator Complex. The covered energy range corresponds to the short internucleonic distances where the relativistic effects and non-nucleonic degrees of freedom can play a significant role.

Non-Proportionality of Organic Scintillators and BGO

According to the present knowledge the non-proportionality of the light yield of scintillators appears to be the fundamental limitation of energy resolution. Thus, the understanding of its origin is of the great importance for a development of new scintillators with enhanced energy resolution. In this respect, the non-proportional response of the typical organic scintillators was studied in comparison to that of a BGO crystal. The studies covered tests of BC408 plastic, BC501A liquid scintillator and anthracene organic crystal. The measurements showed a much larger range of energies presenting non-proportional response compared to that known for inorganic scintillators. In the case of anthracene the non-proportionality covers energy range up to about 500 keV, while for the BC408 plastic and BC501A liquid scintillators, it is above 4 MeV energy lost by gamma quanta. The observed effect can be related to a strong quenching of the light for charged particles in organic scintillators, which is much larger than that observed in inorganic scintillators.

The First Results from “Solar X-ray Spectrometer (SOXS)” Mission

Abstract“Solar X-ray Spectrometer (SOXS)” mission on-board GSAT-2 Indian spacecraft was launched on 08 May 2003 by GSLV-D2 and deployed in geostationery orbit to study the X-ray emission from solar flares with high spectral and temporal resolution. The SOXS consists of two independent payloads viz. SOXS Low Energy Detector (SLD) payload, and SOXS High Energy Detector (SHD) payload. The SLD consists of two solid state detectors Si PIN and CZT, which cover the energy range from 4-60 keV, while the SHD has NaI(Tl)/CsI(Na) sandwiched phoswich detector that covers energy range from 20 keV to 10 MeV. We present very briefly the science objectives and instrumentation of SLD payload. After the successful In-orbit Tests (IOT), the first light was fed into SLD payload on 08 June 2003 when the solar flare was already in progress. We briefly present the first results from the SLD payload.

Effect of the neutral charge fraction in the Coulomb explosion of H 2+ ions through aluminum foils

The Coulomb explosion of the proton fragments dissociated from H 2 + molecules moving through thin aluminum foils has been studied by means of their energy spectra, measured in the forward direction, and by computer simulations. The covered energy range goes from 25 to 100 keV/u. Estimations of the neutral charge fraction of the fragments inside the foil have been obtained by comparison of the experimental energy spectra with the computer simulations.

Precise measurements of cosmic-ray hydrogen and helium spectra with BESS

A series of Balloon-borne Experiments with a Superconducting Spectrometer, BESS, has been made since 1993. We report here the absolute cosmic-ray proton and helium spectra in energy ranges of 1 to 120 GeV and 1 to 54 GeV / nucleon, respectively, as measured by the 1998 balloon flight of the BESS spectrometer. Those spectra were determined within overall uncertainties of ±5 % for protons and ±10 % for helium nuclei including statistical and systematic errors. The covered energy range is relevant to the atmospheric neutrinos observed as “fully contained events” in Super-Kamiokande. In order to extend the energy range up to around 1 TeV, we have started to design and develop new tracking detectors. Those energy spectra in a higher energy region will help to estimate the interstellar spectra of primary cosmic rays and the absolute fluxes of “up-going muons.”

Total cross section for p+d-->p+d+ pi 0 close to threshold.

The total cross section for pion production in the reaction pd\ensuremath{\rightarrow}pd${\mathrm{\ensuremath{\pi}}}^{0}$ has been measured for bombarding energies from ${\mathit{T}}_{\mathit{p}}$=208.4 MeV to 294.6 MeV. This corresponds to maximum pion momenta \ensuremath{\eta}=${\mathit{p}}_{\mathrm{\ensuremath{\pi}},\mathrm{c}.\mathrm{m}.}$/${\mathit{m}}_{\mathrm{\ensuremath{\pi}}}$c between 0.099 and 0.96. The experiment was performed using an electron-cooled proton beam and an internal deuterium gas jet target. The resulting ${\mathrm{\ensuremath{\sigma}}}_{\mathrm{tot}}$ changes by almost four orders of magnitude over the covered energy range. The results are compared to a model which assumes quasi-free production via the pn\ensuremath{\rightarrow}d${\mathrm{\ensuremath{\pi}}}^{0}$ elementary process.

Angular resolved energy distribution of secondary ions emitted from a silicon target sputtered by rare gas ions under oblique incidence

In a UHV experimental apparatus, a silicon target has been sputtered by rare gas ions (Ne, Ar, Kr, Xe) with an incidence angle of 45° measured with respect to the surface normal. Angular resolved energy distributions of the emitted secondary ions have been measured. The covered energy range vary from 1 eV to 3 keV and the emission angle, measured with respect to the target surface normal, vary from −5° to 90°. From these distributions it is assumed that the secondary ions can be divided in two populations. The greater corresponds to particles emitted according to the linear cascade theory. They are characterised by a most probable energy of about few eV and an angular distribution symmetric with respect to the target surface normal. The second ionic population corresponds to energetic ions (few hundred eV) with an angular distribution oriented in a forward direction near the specular reflexion direction of the primary beam. The influence of the primary ion mass M p = 20, 40, 84,129) and of the primary ion energy (in the range 5 to 15 keV) on the secondary ions sharing in these two populations is discussed.