Beta-delayed-neutron studies of 135,136^{135,136}Sb and 140^{140}I performed with trapped ions

Beta-delayed-neutron ($\beta$n) spectroscopy was performed using the Beta-decay Paul Trap and an array of radiation detectors. The $\beta$n branching ratios and energy spectra for $^{135,136}$Sb and $^{140}$I were obtained by measuring the time of flight of recoil ions emerging from the trapped ion cloud. These nuclei are located at the edge of an isotopic region identified as having $\beta$n branching ratios that impact the r-process abundance pattern around the A~130 peak. For $^{135,136}$Sb and $^{140}$I, $\beta$n branching ratios of 14.6(11)%, 17.6(28)%, and 7.6(28)% were determined, respectively. The $\beta$n energy spectra obtained for $^{135}$Sb and $^{140}$I are compared with results from direct neutron measurements, and the $\beta$n energy spectrum for $^{136}$Sb has been measured for the first time

β -decay half-lives of Sb 134,134m and their isomeric yield ratio produced by the spontaneous fission of Cf 252

A number of fission products possess isomeric states which have a nuclear spin significantly different from that of the ground state. The yield ratio of these states following fission is influenced by the angular momentum present in the fissioning system. The Sb134m,134 yield ratio had not been previously measured in the spontaneous fission of Cf252; however, it had previously been observed to favor the (7-) isomer over the (0-) ground state in U235(nth,f) and Th232(25 MeV p,f). Using a mass-separated beam of low-energy Sb134,134m ions produced by Cf252 spontaneous fission at the CARIBU facility, β particles and γ rays were detected using the SATURN/X-Array decay station to determine the fission-yield ratio and β-decay half-lives. The Sb134m to Sb134 fission yield was determined to be 2.03±0.05 and the half-lives of Sb134m and Sb134 were found to be 9.87±0.08 s and 0.674±0.004 s, respectively. These results represent the first isomeric yield ratio measurement for this nucleus, and improved measurements of the Sb134 ground state and the Sb134m isomer half-lives

Recoil ions from the β decay of Sb 134 confined in a Paul trap

The low-energy recoiling ions from the β decay of Sb134 were studied by using the Beta-decay Paul Trap. Using this apparatus, singly charged ions were suspended in vacuum at the center of a detector array used to detect emitted β particles, γ rays, and recoil ions in coincidence. The recoil ions emerge from the trap with negligible scattering, allowing β-decay properties and the charge-state distribution of the daughter ions to be determined from the β-ion coincidences. First-forbidden β-decay theory predicts a β-ν correlation coefficient of nearly unity for the 0- to 0+ transition from the ground state of Sb134 to the ground state of Te134. Although this transition was expected to have a nearly 100% branching ratio, an additional 17.2(52)% of the β-decay strength must populate high-lying excited states to obtain an angular correlation consistent with unity. The extracted charge-state distribution of the recoiling ions was compared with existing β-decay results and the average charge state was found to be consistent with the results from lighter nuclei

The use of cosmic-ray muons in the energy calibration of the Beta-decay Paul Trap silicon-detector array

This article presents an approach to calibrate the energy response of double-sided silicon strip detectors (DSSDs) for low-energy nuclear-science experiments by utilizing cosmic-ray muons. For the 1-mm-thick detectors used with the Beta-decay Paul Trap, the minimum-ionizing peak from these muons provides a stable and time-independent in situ calibration point at around 300 keV, which supplements the calibration data obtained above 3 MeV from α sources. The muon-data calibration is achieved by comparing experimental spectra with detailed Monte Carlo simulations performed using GEANT4 and CRY codes. This additional information constrains the calibration at lower energies, resulting in improvements in quality and accuracy

Effects of Crystalline Amino Acid Concentrations With or Without Formaldehyde Treatment of Diets on Nursery Pig Growth Performance and Fecal Bacterial Concentration

A total of 1,235 nursery pigs (PIC 359 × 1050; initially 26.9 lb BW) were used in a 28-d study evaluating the effects of crystalline amino acid concentrations with or without formaldehyde treatment of diets on nursery pig growth performance, feed bacteria concentration, lysine content, and fecal microbial diversity. Sal CURB (Kemin Industries Inc., Des Moines, IA) is a commercial formaldehyde product that is commonly utilized in the poultry industry for Salmonella control in feed but has also been shown to reduce PEDV infectivity in swine diets.Pigs were weaned at approximately 21 d, fed a common starter diet for 10 d, and allotted to pens based on BW in a completely randomized design. Experimental diets were fed in 2 phases (phase 1, d 0 to 12; and phase 2, 12 to 28 post-weaning) in meal form. Experimental treatments were arranged as a 2 × 2 + 1 factorial with main effects of formaldehyde (none vs. 0.30% in all phases) and crystalline AA concentration (low vs. high) plus a positive control. The positive control represented this current production system’s formulated Lys requirement needed to maximize performance, whereas treatment diets were formulated at 80% of the positive control’s lysine concentration. Feed bacterial concentration was determined by performing aerobic plate, Enterobacteriaceae, and total coliform counts on composited feed samples collected from each batch of feed manufactured at the feed mill and directly from feeders at the farm. Total, available, and free Lys analyses were conducted on composited feed samples collected from each phase of the study to determine Lys content. A composite fecal sample was collected from 3 randomly selected pigs per pen on d 28 for each treatment, DNA isolated, and each sample assessed for bacterial community analysis.Overall, a significant crystalline AA × formaldehyde interaction (P \u3c 0.05) was observed for ADFI and F/G. The interaction for ADFI was because added formaldehyde in high crystalline AA diets decreased feed intake; however, in low crystalline AA diets, ADFI was unchanged. For F/G, pigs had improved F/G in low crystalline AA diets without formaldehyde, but no difference was observed in high crystalline AA diets. Despite the interaction for ADFI and F/G, formaldehyde-treated diets reduced (P \u3c 0.05) ADG, ADFI, and resulted in poorer F/G. Crystalline AA concentration did not impact performance. Added formaldehyde reduced or eliminated bacterial concentration of complete feed in phase 1 of the study. Formaldehyde reduced total and available Lys in both low and high crystalline AA diets, with a greater reduction occurring in low crystalline AA diets, but had no effect on free Lys. Added formaldehyde reduced (P = 0.001) Lactobacillaceae bacterial species, but increased (P = 0.001) Clostridiaceae bacterial species in fecal microbial samples. As expected, formaldehyde treatment reduced bacterial microflora of complete feeds. Overall, the level of crystalline AA did not impact performance while the nursery diet formaldehyde addition negatively influenced growth performance, AA utilization, and fecal microbial diversity

β-delayed neutron emission studies of i 137,138 and Cs 144,145 performed with trapped ions

A detailed study of the β-delayed neutron emission properties of I137,138 and Cs144,145 has been performed by confining ions in the Beta-decay Paul Trap. The daughter ions following β decay emerge from the trapped-ion cloud with negligible scattering allowing reconstruction of the recoil-ion energy from the time of flight. From this information, the neutron-emission branching ratios and neutron-energy spectra were deduced. The results for the I137 and Cs144,145 decays are in agreement with previous results performed using direct neutron-detection techniques. In the case of I138, a branching ratio of 6.18(50)% is obtained, yielding a value consistent with the more recent results, which are a factor of two larger than measurements made prior to 1978

Astrophysical structures from primordial quantum black holes

The characteristic sizes of astrophysical structures, up to the whole observed Universe, can be recovered, in principle, assuming that gravity is the overall interaction assembling systems starting from microscopic scales, whose order of magnitude is ruled by the Planck length and the related Compton wavelength. This result agrees with the absence of screening mechanisms for the gravitational interaction and could be connected to the presence of Yukawa corrections in the Newtonian potential which introduce typical interaction lengths. This result directly comes out from quantization of primordial black holes and then characteristic interaction lengths directly emerge from quantum field theory.Comment: 11 page

Effect of Medium Chain Fatty Acid Supplementation on Nursery Pig Fecal Microbial Populations

A total of 360 pigs [DNA (Columbus, NE) 400 × 200; initially = 14.8 ± 0.15 lb] were used to evaluate the effects of dietary medium chain fatty acid (MCFA) addition on fecal microbial populations. Upon arrival at the nursery, pigs were randomized to pens (5 pigs per pen) and allowed a 6-d acclimation period, at which point pens of pigs were blocked by body weight (BW) and randomized to dietary treatment (9 pens per treatment). Medium chain fatty acids (Sigma Aldrich, St. Louis, MO) included hexanoic (C6), octanoic (C8), and decanoic (C10), and were guaranteed ≥ 98% purity. Treatment diets were formulated to meet or exceed NRC requirements for 15- to 25-lb pigs. Fecal samples were collected from pigs fed control and 1.5% MCFA blend (1:1:1 ratio C6, C8, and C10) diets on d 0 and d 14 and analyzed using 16s rDNA sequencing. A total of 6 phyla were identified with ≥ 1% relative abundance for at least one of the treatment × day analysis combinations. The largest proportion of relative abundance on a phyla level on d 14 consisted of Firmicutes (54% control, 44% MCFA) and Bacteroidetes (32% control, 43% MCFA). A marginally significant treatment × day interaction was observed in the Proteobacteria phylum (P = 0.080), where relative abundance did not change over time in pigs fed the control diet (P = 0.848), whereas a marginally significant decrease over time was observed in pigs fed the MCFA diet (P = 0.092). There was no evidence of an effect of MCFA addition over time for the relative abundance of the remaining phyla (treatment × day, P ≥ 0.359). The main effect of day indicated a significant increase over time in the Tenericutes phylum (P = 0.008) and a significant decrease over time in the Proteobacteria (P = 0.017) and Spirochaetes phyla (P = 0.020). A Firmicutes:Bacteroidetes ratio was calculated, and there was no evidence of a treatment × day interaction (P = 0.338) or day effect (P = 0.211). A total of 23 microbial families were detected at ≥ 1% relative abundance for at least one of the treatment × day analysis combinations. The families with the greatest relative abundance were Prevotellaceae, Ruminococcaceae, and S24-7 families, which had ≥ 10% relative abundance for at least one of the treatment × day analysis combinations. There was no evidence of an effect of MCFA addition over time on the relative abundance for any family (treatment × day, P ≥ 0.123). For both treatments, a reduction over time was observed for Ruminococcaceae (P = 0.048), Lachnospiraceae (P = 0.004), Christensenellaceae (P = 0.004), Spirochaetaceae (P = 0.029), Bacteroidaceae (P = 0.010), and Succinivibrionaceae (P = 0.029) families. An increase in relative abundance over time was observed for the unclassified Clostridiales (P = 0.019), Clostridiaceae (P \u3c 0.001), unclassified RF39 (P = 0.008), and Clostridiales; and other (P \u3c 0.001) families. No evidence of a difference in alpha diversity was observed for either Chao1 (estimate of species richness) or observed operational taxonomic units (OTUs). In summary, adding 1.5% MCFA blend in swine nursery diets did not appear to significantly alter the composition of fecal microbial populations compared to a control diet using 16s rDNA sequencing analysis. Changes in microbial populations were observed over time with both treatments. Further investigation into the mechanism by which MCFA addition benefits growth performance is necessary. Moreover, additional studies into understanding the interactions between MCFA and the gastrointestinal microbiome are warranted due to its well-known inactivation effects on selected microbes