Nuclear Orientation Thermometry

Abstract

temperature nuclear orientation thermometry, in particular y-ray anisotrwpy therimometry, is discussed both from a theoretical and practical point of view. Detailed information is given on the most often used 7-ray anisotropy TMermnometers, along with a comprehensive descriptiom of the --ray anisotropy technique. The "Co in (hcp) cobalt single crystal F-ray anisotropy thermometer is discussed in considerable detail since it is used more frequently in comparison experiments with other primary thermomreters. Recent experimental results using --ray amisotropy thermometers are also reviewed.

A microkelvin cryogen-free experimental platform with integrated noise thermometry

“…Measuring the temperatures so-attained poses another. The base temperature of dilution refrigerators can be established with nuclear orientation thermometry [23], however this slow technique is not suitable as a practical thermometer for regular use, and is not usable at µK temperatures. Other convenient methods of temperature measurement, such as carbon resistance sensors [24], shot noise in tunnel junctions [25] or Coulomb blockade [26] also prove difficult to implement below a few mK.…”

Correlation and spectrum shape measurements in β-decay probing the standard model

“…To observe γ rays HPGe γ detectors were placed outside of the refrigerator. These were used to determine the temperature of the sample via the anisotropy of the 136 keV γ rays from a calibrated 57 CoFe nuclear orientation thermometer also attached to the sample holder [175]. Since measurements were always performed when the samples were in thermal equilibrium, the Boltzmann distribution of the populations of the nuclear substates makes that the nuclear polarization, P, can be deduced directly from the degree of alignment that is obtained from the γ ray anisotropies.…”

Measurements of the total cross section for the scattering of polarized neutrons from polarizedHe3

“…With the silver powder in place, the thickness of the solid 3 He sample was 4.34 ± 0.09 × 10 22 atoms/cm 2 . The target polarization was extracted from the temperature of the BeCu sample cell, as measured by two independent thermometric standards: a 60 CoCo nuclear orientation thermometer [14] and a 3 He melting curve thermometer (MCT) [15]. The nuclear orientation thermometry required an intrinsic germanium detector to observe the 1.17 MeV and 1.33 MeV γ rays from 60 Co. To avoid radiation damage from neutrons however, the detector had to be removed from the experimental hall whenever beam was on target.…”