Matrix representation of decay schemes

A matrix representation of the scheme of radioactive decay combines the compactness of a tabular form with the positional information of a graphical "decay scheme". The representation is particularly convenient for generation from computer files and printing with "personal computer" types of devices.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26297/1/0000382.pd

Analysis of multidimensional spectra

Coincidence spectra obtained from arrays of radiation detectors can be analyzed without resorting to projecting lower dimensional spectra. The techniques for two-dimensional analysis (peak searches and peak fitting) are described, and extensions to higher dimensions are discussed. Even for two-dimensional analysis it is most efficient to compare predictions from a model, such as a scheme for radioactive decay, with the data by backcalculating the data from the model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43124/1/10967_2005_Article_BF02041514.pd

A gas-jet system for the study of short-lived, light fission products

For the study of short-lived fission products, a gas jet system has been set up in a beam port of the Ford Nuclear Reactor at the University of Michigan. The system consists of a target chamber joined to three polyethylene tubes which serve as gas inlet, fission product outlet and an outlet for pressure monitoring. The target chamber is housed in a 7.6 cm (ID) aluminum tube supported inside a radial beam port. This tube can be withdrawn by ∼1 m, allowing the target chamber to be positioned either close to or ∼1 m from the core. The aluminum tube is surrounded by water, which provides shielding and protects the target when not in use (at ∼1 m position). The target is ∼1 mg of 235 U, chemically plated on an aluminum planchett. The uranium is covered with 2.7 mg·cm −2 of aluminum. The aluminum covering stops most of the heavy fission fragments; the light fission fragments pass through the foil and are thermalized in a gaseous mixture of nitrogen and ethylene. The transport time of fission products from the target chamber to the detector position was measured to be 970 msec. Preliminary experiments indicate that the transport time can be reduced further. The gas jet system is being utilized for the development of fast, gas-phase chemistry for the separation of bromine from fission products.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43134/1/10967_2005_Article_BF02037088.pd

A proposed intense slow positron source based on 58Co

Positron beams have proven very useful for condensed matter and surface research. The highest intensity of the current operating positron beams is ∼109 slow e+/second. The goal of our proposal is to build an Intense Slow Positron Source (ISPS) demonstration beam (Phase I) of unprecedented brightness at the Idaho National Engineering Laboratory, INEL (up to 1010 slow e+/s at 5 keV over a <0.03 cm. diameter). This Phase I beam will prove the principles necessary to build a larger facility scale ISPS Phase II beam which will have a potential of 1013 e+/s, or ≳1012 e+/s over 0.03 cm. The INEL is an ideal location for the ISPS because of the fast breeder reactor EBR‐II, which is perfectly suited to creating the positron emitting isotope 58Co, and the excellent radioactive materials handling capability and expertise. Sufficient expertise is available at INEL for the construction and operation of a user facility (Phase II).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87604/2/289_1.pd

Extracting energies and intensities from complex coincidence matrices

Coincidence intensities and uncertainties are extracted at the statistical limits from [gamma]-[gamma] coincidence matrices. The matrices are decomposed into continuum, ridges and peaks. The continuum is successfully modeled by the product of two vectors which describe the Compton distributions in the coincident detectors or groups of detectors. The ridges are represented by the corresponding continuum vector scaled according to the intensity and energy of the associated [gamma]-ray. The peaks are fitted as the product of two, one-dimensional Gaussians. This technique has been applied to the analysis of prompt gamma-rays from the spontaneous fission of 252Cf and the high spin states in 163Lu populated via the 122Sn(45Sc, 4n) reaction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31115/1/0000011.pd

‘As a farmer you've just got to learn to cope’: Understanding dairy farmers' perceptions of climate change and adaptation decisions in the lower South Island of Aotearoa-New Zealand

The impacts and implications of climate change – such as floods, droughts, heavy rainfall and increased regulation – are affecting dairy farming practices in the lower South Island (Te Waipaounamu) of Aotearoa-New Zealand. Adapting to these changes, in an equitable and transformational manner, is dependent on understanding the underlying root causes of vulnerability alongside local knowledge and values. We apply an intersectional values-based and contextual analysis to describe how past and present processes of agrarian change interact across different farmer identities to influence adaptive pathways. Local knowledge, place-based experience, values and perceptions of fairness intersect with different facets of a farmer's identity – such as financial capacity, land ownership status, debt arrangements, age and gendered participation – to enable or constrain adaptive action. Notably, notions of fairness, whether real or perceived, vary across farmer groups, and influence the kinds of adaptation activities that dairy farmers are willing, or potentially able, to engage in. The results call for more contextualised engagement with farming communities, and highlight the need to build a shared understanding of the complex historical, social, economic, cultural and environmental drivers of past, present and future change, in this highly productive, yet risky, agricultural landscape

Microcomputer control of radiochemical processes

A system for control of radiochemical processes has been designed and constructed. Control passes through a single 8-bit port (6522 VIA) to up to 64 on-off sensors and 64 on-off switches. The outputs are latched; they are switched one at a time.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25522/1/0000063.pd

The Extinction and Distance of Maffei 1

We have obtained low- and high-resolution spectra of the core of the highly-reddened elliptical galaxy Maffei 1. From these data, we have obtained the first measurement of the Mg2 index, and have measured the velocity dispersion and radial velocity with improved accuracy. To evaluate the extinction, a correlation between the Mg2 index and effective V-I colour has been established for elliptical galaxies. Using a new method for correcting for effective wavelength shifts, we find A_V = 4.67 +/- 0.19 mag, which is lower by 0.4 mag than previously thought. To establish the distance, the Fundamental Plane for elliptical galaxies has been constructed in I. The velocity dispersion of Maffei 1, measured to be 186.8 +/- 7.4 km/s, in combination with modern wide-field photometry in I, leads to a distance of 2.92 +/- 0.37 Mpc. The Dn-sigma relation, which is independently calibrated, gives 3.08 +/- 0.85 Mpc and 3.23 +/- 0.67 Mpc from photometry in B and K`, respectively. The weighted mean of the three estimates is 3.01 +/- 0.30 Mpc. The distance and luminosity make Maffei 1 the nearest giant elliptical galaxy. The radial velocity of Maffei 1 is +66.4 +/- 5.0 km/s, significantly higher than the accepted value of -10 km/s. The Hubble distance corresponding to the mean velocity of Maffei 1, Maffei 2 and IC342 is 3.5 Mpc. Thus, it is unlikely that Maffei 1 has had any influence on Local Group dynamics

An overview of the Michigan Positron Microscope Program

An overview of the Michigan Positron Microscope Program is presented with particular emphasis on the second generation microscope that is presently near completion. The design and intended applications of this microscope will be summarized.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87602/2/391_1.pd

Identification and characterization of 3.8 min 134mI

The [gamma]-ray spectra of iodine fractions rapidly separated from the products of slow neutron fission of 235U were studied. A 3.8 +/- 0.2 min species was found and was identified as 134mI from observations of corresponding growth in the intensities of the prominent 847 and 884 keV [gamma]-rays of 53 min 134I. This isomer is analogous to the 2.9 h isomer 134mCs and decays by the sequence 134mI (J[pi] = 8-)(J[pi] = 5+)134I (J[pi] = 4+) by transitions of and 44.4 +/- 0.1 keV(), respectively. For a 316 keV cross-over [gamma]-ray an upper limit of 1 % was obtained, and is near the intensity predicted by M4 systematics. A low-intensity [gamma]-ray of 234.3 +/- 0.5 keV was found This [gamma]-ray is interpreted as evidence for [beta]-decay (2%) of the isomer, possibly to the 0.29 sec 7- isomeric level in 134Xe.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34159/1/0000445.pd