A
bstract
A comprehensive set of azimuthal single-spin and double-spin asymmetries in semi-inclusive leptoproduction of pions, charged kaons, protons, and antiprotons from transversely polarized ...protons is presented. These asymmetries include the previously published HERMES results on Collins and Sivers asymmetries, the analysis of which has been extended to include protons and antiprotons and also to an extraction in a three-dimensional kinematic binning and enlarged phase space. They are complemented by corresponding results for the remaining four single-spin and four double-spin asymmetries allowed in the one-photon-exchange approximation of the semi-inclusive deep-inelastic scattering process for target-polarization orientation perpendicular to the direction of the incoming lepton beam. Among those results, significant non-vanishing cos (
ϕ−ϕ
S
) modulations provide evidence for a sizable worm-gear (II) distribution,
g
1
T
q
x
p
T
2
. Most of the other modulations are found to be consistent with zero with the notable exception of large sin (
ϕ
S
) modulations for charged pions and
K
+
.
Flux-dependent nonlinearity (reciprocity failure) in HgCdTe near-infrared detectors can severely impact an instrument’s performance, in particular, with respect to precision photometric measurements. ...The cause of this effect is presently not understood. To investigate reciprocity failure, a dedicated test system was built. For flux levels between 1 and50,000 photons s-1
50
,
000
photons
s
-
1
, a sensitivity to reciprocity failure of approximately0.1% decade-1
0.1
%
decade
-
1
was achieved. A wavelength-independent nonlinearity due to reciprocity failure of about0.35% decade-1
0.35
%
decade
-
1
was measured in a 1.7 μm HgCdTe detector.
A detailed study of reciprocity failure in four 1.7 μm cutoff HgCdTe near-infrared detectors is presented. The sensitivity to reciprocity failure is approximately0.1% decade-1
0.1
%
decade
-
1
...over up to 5 orders of magnitude in illumination intensity. The four detectors, which represent three successive production runs with modified growth recipes, show large differences in amount and spatial structure of reciprocity failure. Reciprocity failure could be reduced to negligible levels by cooling the detectors to about 110 K. No wavelength dependence was observed. The observed spatial structure appears to be weakly correlated with image persistence.
Wide‐field survey instruments are used to efficiently observe extended regions of the sky. To achieve a large field of view and to provide a high signal‐to‐noise ratio for faint sources, many modern ...instruments are undersampled. However, in undersampled detectors, sensitivity variations across individual pixels can severely impact science programs that require high photometric precision. To address this, a near‐infrared spot projection system has been developed. With this system, 1.7 μm cutoff detectors were characterized, and the effect of subpixel nonuniformity was studied. The measurements demonstrate that for detectors with near 100% internal quantum efficiency, 1% photometry can be achieved with a point‐spread function (PSF) size of about half a pixel. For detectors with large subpixel nonuniformity, photometric errors become negligible only if the PSF size is more than about two pixels.
Solenoid Siberian snakes have successfully maintained polarization in particle rings below 1 GeV, but never in multi-GeV rings, because the spin rotation by a solenoid is inversely proportional to ...the beam momentum. High energy rings, such as Brookhaven’s 255 GeV Relativistic Heavy Ion Collider (RHIC), use only odd multiples of pairs of transverse B-field Siberian snakes directly opposite each other. When it became impractical to use a pair of Siberian Snakes in Fermilab’s 120GeV/c Main Injector, we searched for a new type of single Siberian snake that could overcome all depolarizing resonances in the 8.9–120GeV/c range. We found that a snake made of one 4-twist helix and 2 dipoles could maintain the polarization. This snake design could solve the long-standing problem of significant polarization loss during acceleration of polarized protons from a few GeV to tens of GeV, such as in the AGS, before injecting them into multi-hundred GeV rings, such as RHIC.
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