Measurement of absolute γ-ray emission probabilities in the decay of U.

Accurate measurements were performed of the photon emission probabilities following the α decay of U to Th. Sources of highly enriched U were characterised in terms of isotopic composition by mass spectrometry and their activities were standardised by means of alpha-particle counting at a low defined solid angle. The standardised sources were subsequently measured by high-resolution γ-ray spectrometry with calibrated high-purity germanium detectors to determine the photon emission probabilities.

Preparation of thick uranium layers on aluminium and stainless steel backings.

The methods of electrodeposition and "molecular plating" were studied for the production of uranium targets with an areal density up to 0.6 mg cm(-2) on aluminium and up to 1.5 mg cm(-2) on stainless steel backings from aqueous and organic electrolytes.

Multi-layer ²³⁵UF₄-⁶LiF-Au targets for high-resolution fission fragment measurements.

Multi-layer (235)UF4-(6)LiF-Au targets have been produced by vacuum deposition on thin polyimide foils with an areal density, measured by spectrophotometry, of about 33µgcm(-2). The foils were first covered with an Au-layer and then, with a second layer of (6)LiF, both by vapour deposition. The (235)UF4 layer was prepared by fluoride sublimation.

Measurement of the Neutron Lifetime by Counting Trapped Protons.

We measured the neutron decay lifetime by counting in-beam neutron decay recoil protons trapped in a quasi-Penning trap. The absolute neutron beam fluence was measured by capture in a thin (6)LiF foil detector with known efficiency. The combination of these measurements gives the neutron lifetime: τ n = (886.

Measurement of the neutron lifetime using a proton trap.

We report a new measurement of the neutron decay lifetime by the absolute counting of in-beam neutrons and their decay protons. Protons were confined in a quasi-Penning trap and counted with a silicon detector. The neutron beam fluence was measured by capture in a thin 6LiF foil detector with known absolute efficiency.