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Caleb Marshall

Publications and source records attributed to Caleb Marshall.

20 records · Page 2Linked to original sources

Reaction rates for the $^{39}$K(p,$γ$)$^{40}$Ca reaction

The magnesium-potassium anti-correlation observed in globular cluster NGC2419 can be explained by nuclear burning of hydrogen in hot environments. The exact site of this nuclear burning is, as yet, unknown. In order to constrain the sites responsible for this anti-correlation, the nuclear reactions involved must be well understood. The $^{39}$K+p reactions are one such pair of reactions. Here, we report a new evaluation of the $^{39}$K(p,$γ$)$^{40}$Ca reaction rate by taking into account ambiguities and measurement uncertainties in the nuclear data. The uncertainty in the $^{39}$K(p,$γ$)$^{40}$Ca reaction rate is larger than previously assumed, and its influence on nucleosynthesis models is demonstrated. We find the $^{39}$K(p,$γ$)$^{40}$Ca reaction cross section should be the focus of future experimental study to help constrain models aimed at explaining the magnesium-potassium anti-correlation in globular clusters.

nucl-ex↗

The Focal plane Detector Package on the TUNL Split-pole Spectrograph

A focal plane detector for the Enge Split-pole Spectrograph at Triangle Universities Nuclear Laboratory has been designed. The detector package consists of two position sensitive gas avalanche counters, a gas proportionality energy loss section, and a residual energy scintillator. This setup allows both particle identification and focal plane reconstruction. In this paper we will detail the construction of each section along with their accompanying electronics and data acquisition. Effects of energy loss throughout the detector, ray tracing procedures, and resolution as a function of fill pressure and bias voltage are also investigated. A measurement of the $^{27}\!$Al$(d,p)$ reaction is used to demonstrate detector performance and to illustrate a Bayesian method of energy calibration.

physics.ins-det↗