Spin correlation measurements in nucleon‐nucleon scattering at high energies

Recent high energy measurements of spin correlation parametrs are reviewed and discussed in terms of recent theoretical models.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87675/2/11_1.pd

Polarimeter working group—Summary

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87527/2/111_1.pd

Measurement of A and ANN in p↑ p↑ elastic scattering at 18.5 GeV/c

 As part of a continuing study of spin effects in pp−interactions, we have measured the analyzing power, A, and the spin correlation parameter, ANN, in p↑p↑ elastic scattering in the p⟂2 range 1.4 to 3.35 (GeV/c)2. The experiment was carried out using a polarized proton beam at the AGS at Brookhaven National Laboratory together with a polarized proton target. The intensity, polarization, and reliability of the polarized proton beam have improved significantly since the first commissioning in 1984. These improvements have allowed a systematic study at a single energy with good precision, rather than the more scattered measurements possible in the earlier runs.  (AIP)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87665/2/1163_1.pd

Improving Visual Field Examination of the Macula Using Structural Information

Purpose: To investigate a novel approach for structure-function modeling in glaucoma to improve visual field testing in the macula. Methods: We acquired data from the macular region in 20 healthy eyes and 31 with central glaucomatous damage. Optical coherence tomography (OCT) scans were used to estimate the local macular ganglion cell density. Perimetry was performed with a fundus-tracking device using a 10-2 grid. OCT scans were matched to the retinal image from the fundus perimeter to accurately map the tested locations onto the structural damage. Binary responses from the subjects to all presented stimuli were used to calculate the structure-function model used to generate prior distributions for a ZEST (Zippy Estimation by Sequential Testing) Bayesian strategy. We used simulations based on structural and functional data acquired from an independent dataset of 20 glaucoma patients to compare the performance of this new strategy, structural macular ZEST (MacS-ZEST), with a standard ZEST. Results: Compared to the standard ZEST, MacS-ZEST reduced the number of presentations by 13% in reliable simulated subjects and 14% with higher rates (≥20%) of false positive or false negative errors. Reduction in mean absolute error was not present for reliable subjects but was gradually more important with unreliable responses (≥10% at 30% error rate). Conclusions: Binary responses can be modeled to incorporate detailed structural information from macular OCT into visual field testing, improving overall speed and accuracy in poor responders. Translational Relevance: Structural information can improve speed and reliability for macular testing in glaucoma practice

Refinement and preliminary evaluation of two tablet-based tests of real-world visual function

PURPOSE: To describe, refine, evaluate, and provide normative control data for two freely available tablet-based tests of real-world visual function, using a cohort of young, normally-sighted adults. METHODS: Fifty young (18-40 years), normally-sighted adults completed tablet-based assessments of (1) face discrimination and (2) visual search. Each test was performed twice, to assess test-retest repeatability. Post-hoc analyses were performed to determine the number of trials required to obtain stable estimates of performance. Distributions were fitted to the normative data to determine the 99% population-boundary for normally sighted observers. Participants were also asked to rate their comprehension of each test. RESULTS: Both tests provided stable estimates in around 20 trials (~1-4 min), with only a further reduction of 14%-17% in the 95% Coefficient of Repeatability (CoR95 ) when an additional 40 trials were included. When using only ~20 trials: median durations for the first run of each test were 191 s (Faces) and 51 s (Search); test-retest CoR95 were 0.27 d (Faces) and 0.84 s (Search); and normative 99% population-limits were 3.50 d (Faces) and 3.1 s (Search). No participants exhibited any difficulties completing either test (100% completion rate), and ratings of task-understanding were high (Faces: 9.6 out of 10; Search: 9.7 out of 10). CONCLUSIONS: This preliminary assessment indicated that both tablet-based tests are able to provide simple, quick, and easy-to-administer measures of real-world visual function in normally-sighted young adults. Further work is required to assess their accuracy and utility in older people and individuals with visual impairment. Potential applications are discussed, including their use in clinic waiting rooms, and as an objective complement to Patient Reported Outcome Measures (PROMs)

Sum rules for spin asymmetries

Starting from rotational invariance we derive sum rules for the single-spin asymmetries in inclusive production and binary processes. We also get sum rules for spin correlation parameters in elastic pp-scattering.Comment: 4 page

Electron Spin Precession at CEBAF

The nuclear physics experiments at the Thomas Jefferson National Accelerator Facility often require longitudinally polarized electrons to be simultaneously delivered to three experimental halls. The degree of longitudinal polarization to each hall varies as function of the accelerator settings, making it challenging in certain situations to deliver a high degree of longitudinal polarization to all the halls simultaneously. Normally, the degree of longitudinal polarization the halls receive is optimized by changing the initial spin direction at the beginning of the machine with a Wien filter. Herein, it is shown that it is possible to further improve the degree of longitudinal polarization for multiple experimental halls by redistributing the energy gain of the CEBAF linacs while keeping the total energy gain fixed.Comment: 4 pages, 3 figures, to appear in the proceedings of the 18th International Symposium on Spin Physics (SPIN2008

Polarization measurements on irradiated ammonia

The polarization characteristics of ammonia irradiated at liquid helium temperatures and subsequently used in a scattering experiment are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87408/2/488_1.pd

Horizontal dilution refrigerator for use in intense proton beams

A fast loading high‐power horizontal dilution refrigerator insert has been built for use in the Michigan Polarized Proton Target (PPT V). This PPT will be used in measurements of spin effects in high P⟂ elastic p−p scattering at the Brookhaven AGS. The cooling power is compared with the existing interchangeable 3He evaporation insert, and with similar dilution refrigerators at CERN and Bonn. The relative merits of these two types of refrigerators in absorbing the heat loads of high intensity beams is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87406/2/492_1.pd