Precision Mass Measurements of Neutron-Rich Neodymium and Samarium Isotopes and Their Role in Understanding Rare-Earth Peak Formation

The Canadian Penning Trap mass spectrometer at the Californium Rare Isotope Breeder Upgrade (CARIBU) facility was used to measure the masses of eight neutron-rich isotopes of Nd and Sm. These measurements are the first to push into the region of nuclear masses relevant to the formation of the rare-earth abundance peak at A∼165 by the rapid neutron-capture process. We compare our results with theoretical predictions obtained from "reverse engineering" the mass surface that best reproduces the observed solar abundances in this region through a Markov chain Monte Carlo technique. Our measured masses are consistent with the reverse-engineering predictions for a neutron star merger wind scenario.

Dynamical collective calculation of supernova neutrino signals

We present the first calculations with three flavors of collective and shock wave effects for neutrino propagation in core-collapse supernovae using hydrodynamical density profiles and the S matrix formalism. We explore the interplay between the neutrino-neutrino interaction and the effects of multiple resonances upon the time signal of positrons in supernova observatories. A specific signature is found for the inverted hierarchy and a large third neutrino mixing angle and we predict, in this case, a dearth of lower energy positrons in Cherenkov detectors midway through the neutrino signal and the simultaneous revelation of valuable information about the original fluxes. We show that this feature is also observable with current generation neutrino detectors at the level of several sigmas.

Reconstructing supernova-neutrino spectra using low-energy beta beams

Neutrinos are the principal messengers reaching us from the center of a supernova. Terrestrial neutrino telescopes can provide precious information about the processes in the core of the star. But the information that a neutrino detector can supply is restricted by the fact that little experimental data on the neutrino-nucleus cross sections exist and by the uncertainties in theoretical calculations. In this Letter, we propose a novel procedure that determines the response of a target nucleus in a supernova-neutrino detector, by using low-energy beta beams. We show that fitting "synthetic" spectra, constructed by taking linear combinations of beta-beam spectra, to the original supernova-neutrino spectra reproduces the folded differential cross sections very accurately. Comparing the response in a detector to these synthetic responses provides a direct way to determine the main parameters of the supernova-neutrino energy distribution.

Optimal visualization of esophageal varices

Twelve patients with known esophageal varices and willingness to cooperate were included in the study. Medications administered were placebo, 2 mg of glucagon, and 30 mg of propantheline bromide. All medications were given double-blind and crossover. On the basis of this study the authors believe that for optimal visualization of esophageal varices the following is the procedure of choice: (1) the patient should remain horizontal (this is best done in the left lateral position for comfort and ease of expectoration) for ten minutes after swallowing high density barium; (2) the patient should "clear his throat" frequently and expectorate all saliva (barium sticks to the pharynx and makes the patient want to swallow and "clearing his throat" by forced expiration helps the patient to expectorate this coating and prevents swallowing); (3) filming should be done in expiration in the supine (left posterior oblique to table top) position; and (4) in equivocal cases the examination can be repeated with an anticholinergic drug if the patient has no contraindications to its use. The patient should empty his bladder just before administration of the drug. The intelligent use of these factors should result in a saving of both fluoroscopic time and film, and give the radiologist a safe optimal diagnostic yield.