Beyond fifth generation (5G) communication systems aim towards data rates in the tera bits per second range, with improved and flexible coverage options, introducing many new technological challenges ...in the fields of network architecture, signal processing, and radio frequency front-ends. One option is to move towards cell-free, or distributed massive Multiple-Input Multiple-Output (MIMO) network architectures and highly integrated front-end solutions. This paper presents an outlook on beyond 5G distributed massive MIMO communication systems, the signal processing, characterisation and simulation challenges, and an overview of the state of the art in millimetre wave antennas and electronics.
Solubilities of neptunium and plutonium were studied in J-13 groundwater (ionic strength of about 3.7 mmol; total dissolved carbonate of 2.8 mmol) from the proposed Yucca Mountain Nuclear Waste ...Repository site, Nevada, at three different temperatures (25, 60, and 90 °C) and pH values (6.0, 7.0, and 8.5). Experiments were performed from both over- and undersaturation at defined CO2 partial pressures. The solubility of 237Np from oversaturation ranged from a high of (9.40 ± 1.22) × 10-4 M at pH 6.0 and 60 °C to a low of (5.50 ± 1.97) × 10-6 M at pH 8.5 and 90 °C. The analytical results of solubility experiments from undersaturation (temperatures of 25 and 90 °C and pH values 6, 7, and 8.5) converged on these values. The 239/240Pu solubilities ranged from (4.70 ± 1.13) × 10-8 M at pH 6.0 and 25 °C to (3.62 ± 1.14) × 10-9 M at pH 8.5 and 90 °C. In general, both neptunium and plutonium solubilities decreased with increasing pH and temperature. Greenish-brown crystalline Np2O5·xH2O was identified as the solubility-limiting solid using X-ray diffraction. A mean thermodynamic solubility product for Np2O5·xH2O of log K°sp = 5.2 ± 0.8 for the reaction Np2O5·xH2O + 2 H+ ⇌ 2NpO2 + + (x+1)H2O at 25 °C was calculated. Sparingly soluble Pu(IV) solids, PuO2·xH2O and/or amorphous plutonium(IV) hydroxide/colloids, control the solubility of plutonium in J-13 water.
The goal of nuclear forensics is to establish an unambiguous link between illicitly trafficked nuclear material and its origin. The Los Alamos National Laboratory (LANL) Nuclear Materials Signatures ...Program has implemented a graded “conduct of operations” type analysis flow path approach for determining the key nuclear, chemical, and physical signatures needed to identify the manufacturing process, intended use, and origin of interdicted nuclear material. This analysis flow path includes both destructive and non-destructive characterization techniques and has been exercized against different nuclear materials from LANL’s special nuclear materials archive. Results obtained from the case study will be presented to highlight analytical techniques that offer the critical attribution information.
Enhanced decay of the 31-yr isomer of (178)Hf induced by x-ray irradiation has been reported previously. Here we describe an attempt to reproduce this result with an intense "white" x-ray beam from ...the Advanced Photon Source. No induced decay was observed. The upper limits for the energy-integrated cross sections for such a process, over the range of energies of 20--60 keV x rays, are less than 2 x 10(-27) cm(2) keV, below the previously reported values by more than 5 orders of magnitude; at 8 keV the limit is 5 x 10(-26) cm(2) keV.
The Sudbury Neutrino Observatory (SNO) used an array of {sup 3}He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active ...({nu}{sub x}) {sup 8}B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54{sub -0.31}{sup +0.33}(stat){sub -0.34}{sup +0.36}(syst)x10{sup 6} cm{sup -2} s{sup -1}, in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields {delta}m{sup 2}=7.59{sub -0.21}{sup +0.19}x10{sup -5} eV{sup 2} and {theta}=34.4{sub -1.2}{sup +1.3} degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.
The Sudbury Neutrino Observatory (SNO) used an array of 3He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active (nu_x) ...8B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54_-0.31;+0.33(stat)-0.34+0.36(syst)x10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields Deltam2=7.59_-0.21;+0.19x10(-5) eV2 and theta=34.4_-1.2;+1.3 degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.
An array of Neutral-Current Detectors (NCDs) has been built in order to make a unique measurement of the total active flux of solar neutrinos in the Sudbury Neutrino Observatory (SNO). Data in the ...third phase of the SNO experiment were collected between November 2004 and 2006, after the NCD array was added to improve the neutral-current sensitivity of the SNO detector. This array consisted of 36 strings of proportional counters filled with a mixture of
3He and CF
4 gas capable of detecting the neutrons liberated by the neutrino-deuteron neutral-current reaction in the D
2O, and four strings filled with a mixture of
4He and CF
4 gas for background measurements. The proportional counter diameter is 5
cm. The total deployed array length was 398
m. The SNO NCD array is the lowest-radioactivity large array of proportional counters ever produced. This article describes the design, construction, deployment, and characterization of the NCD array, discusses the electronics and data acquisition system, and considers event signatures and backgrounds.
Iron isotopes offer an excellent opportunity for detailed tracing of natural processes because of the range of stable isotopes (54,56,57,58) and the importance of Fe redox transitions in biochemical ...and inorganic processes. A significantly improved mass spectrometric technique is described for Fe isotopic analysis that utilized ion pulse counting detection and is calibrated with an absolute Fe isotope abundance standard. All four stable Fe isotopes are quantified in a single analysis to approx 0.1% precision and accuracy using a low-temperature (1200 deg C) silica gel/boric acid technique on an improved source filament assembly composed of platinum and ceramic. Filament loads of 100-1000 ng can be utilized through implementation of an ultraclean work environment, improved chemistry, and a source designed specifically to minimize isobaric interference in the mass 50-60 region.
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