Characterization of solidified gas thin film targets via alpha particle energy loss

Abstract

A method is reported for measuring the thickness and uniformity of thin films of solidified gas targets. The energy of α particles traversing the film is measured and the energy loss is converted to thickness using the stopping power. The uniformity is determined by measuring the thickness at different positions with an array of sources. Monte Carlo simulations have been performed to study the film deposition mechanism. Thickness calibrations for a TRIUMF solid hydrogen target system are presented.

Resonant Formation ofdμtMolecules in Deuterium: An Atomic Beam Measurement of Muon CatalyzeddtFusion

“…2(a)) were prepared by rapidly freezing a hydrogen isotope or mixture onto the gold foils, held at 3.5 K in an ultra-high vacuum of order 10 −9 torr or better. The layer thickness and uniformity were characterized off-line via energy loss of α particles [12], and the effective thickness was then derived using a separate measurement [13] of the muon beam profile (about 30 mm diameter). The time between the µ entrance signal and the detection of a fusion α (which we call fusion time) is dominated by µt TOF and provides information on molecular formation energy, as long as the energy loss (∆E µt ) of µt, due to elastic scattering before the formation in the DS D 2 , is small.…”

Time-of-Flight Spectroscopy of Muonic Hydrogen Atoms and Molecules

“…5. Calibration measurement of solid hydrogen film layer thickness via energy loss of α particles [27,28]. Americium α source is embedded on the surface of the goldplated copper substrate, onto which hydrogen thin film is deposited by releasing the gas through porous sintered metal (diffuser).…”