scholarly journals Measurement of low energy ionization signals from Compton scattering in a charge-coupled device dark matter detector

2017 ◽  
Vol 96 (4) ◽  
Author(s):  
K. Ramanathan ◽  
A. Kavner ◽  
A. E. Chavarria ◽  
P. Privitera ◽  
D. Amidei ◽  
...  
Keyword(s):  
Dark Matter ◽  
Compton Scattering ◽  
Low Energy ◽  
Charge Coupled Device ◽  
A Charge

scholarly journals Detecting Cold Dark Matter Candidates

1987 ◽  
Vol 117 ◽  
pp. 490-490
Author(s):  
A. K. Drukier ◽  
K. Freese ◽  
D. N. Spergel
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Galactic Halo ◽  
Dark Matter Particle ◽  
Low Energy ◽  
The Sun ◽  
Background Rate ◽  
System Noise ◽  
Weakly Interacting ◽  
Massive Neutrinos

We consider the use of superheated superconducting colloids as detectors of weakly interacting galactic halo candidate particles (e.g. photinos, massive neutrinos, and scalar neutrinos). These low temperature detectors are sensitive to the deposition of a few hundreds of eV's. The recoil of a dark matter particle off of a superheated superconducting grain in the detector causes the grain to make a transition to the normal state. Their low energy threshold makes this class of detectors ideal for detecting massive weakly interacting halo particles.We discuss realistic models for the detector and for the galactic halo. We show that the expected count rate (≈103 count/day for scalar and massive neutrinos) exceeds the expected background by several orders of magnitude. For photinos, we expect ≈1 count/day, more than 100 times the predicted background rate. We find that if the detector temperature is maintained at 50 mK and the system noise is reduced below 5 × 10−4 flux quanta, particles with mass as low as 2 GeV can be detected. We show that the earth's motion around the Sun can produce a significant annual modulation in the signal.

scholarly journals Spectroscopic flat-fields can be used for precision CCD gain and noise tests

2021 ◽  
Vol 38 ◽  
Author(s):  
J. Gordon Robertson
Keyword(s):  
Ccd Camera ◽  
Matched Pair ◽  
Optical Fibres ◽  
Charge Coupled Device ◽  
Small Areas ◽  
Flat Field ◽  
Basic Parameters ◽  
The Mean ◽  
A Charge ◽  
Analogue To Digital

Abstract One of the basic parameters of a charge coupled device (CCD) camera is its gain, that is, the number of detected electrons per output Analogue to Digital Unit (ADU). This is normally determined by finding the statistical variances from a series of flat-field exposures with nearly constant levels over substantial areas, and making use of the fact that photon (Poisson) noise has variance equal to the mean. However, when a CCD has been installed in a spectroscopic instrument fed by numerous optical fibres, or with an echelle format, it is no longer possible to obtain illumination that is constant over large areas. Instead of making do with selected small areas, it is shown here that the wide variation of signal level in a spectroscopic ‘flat-field’ can be used to obtain accurate values of the CCD gain, needing only a matched pair of exposures (that differ in their realisation of the noise). Once the gain is known, the CCD readout noise (in electrons) is easily found from a pair of bias frames. Spatial stability of the image in the two flat-fields is important, although correction of minor shifts is shown to be possible, at the expense of further analysis.

Detailed Performance Analysis of a 10kW Dish∕Stirling System

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
W. Reinalter ◽  
S. Ulmer ◽  
P. Heller ◽  
T. Rauch ◽  
J.-M. Gineste ◽  
...  
Keyword(s):  
Electric Energy ◽  
Optical Quality ◽  
Stirling Engine ◽  
Thermodynamic Efficiency ◽  
Ambient Conditions ◽  
Camera System ◽  
Charge Coupled Device ◽  
Mapping System ◽  
Conversion Unit ◽  
A Charge

The CNRS-Promes dish∕Stirling system was erected in Jun. 2004 as the last of three country reference units built in the “Envirodish” project. It represents the latest development step of the EuroDish system with many improved components. With a measured peak of 11kW electrical output power, it is also the best performing system so far. The measurement campaign to determine the optical and thermodynamic efficiency of the system is presented. The optical quality of the concentrator and the energy input to the power conversion unit was measured with a classical flux-mapping system using a Lambertian target and a charge coupled device camera system. An efficiency of the concentrator including the intercept losses of 74.4% could be defined for this particular system. For the thermodynamic analysis all the data necessary for a complete energy balance around the Stirling engine were measured or approximated by calculations. For the given ambient conditions during the tests, a Stirling engine efficiency of 39.4% could be measured. The overall efficiency for the conversion of solar to electric energy was 22.5%.

Soft X-ray continuum radiation from low-energy pinch discharges of hydrogen

2013 ◽  
Vol 79 (5) ◽  
pp. 489-507 ◽  
Author(s):  
R. MILLS ◽  
R. BOOKER ◽  
Y. LU
Keyword(s):  
Extreme Ultraviolet ◽  
Low Energy ◽  
Pure Hydrogen ◽  
Charge Coupled Device ◽  
Energetic Ions ◽  
Continuum Radiation ◽  
High Kinetic Energy ◽  
Extreme Ultraviolet Radiation ◽  
Electrode Metal ◽  
Detector Chamber

AbstractUnder a study contracted by GEN3 Partners, spectra of high current pinch discharges in pure hydrogen and helium were recorded in the extreme ultraviolet radiation region at the Harvard Smithsonian Center for Astrophysics (CfA) in an attempt to reproduce experimental results published by BlackLight Power, Inc. (BLP) showing predicted continuum radiation due to hydrogen in the 10–30 nm region (Mills, R. L. and Lu, Y. 2010 Hydrino continuum transitions with cutoffs at 22.8 nm and 10.1 nm. Int. J. Hydrog. Energy35, 8446–8456, doi:10.1016?j.ijhydene.2010.05.098). Alternative explanations were considered to the claimed interpretation of the continuum radiation as being that emitted during transitions of H to lower-energy states (hydrinos). Continuum radiation was observed at CfA in the 10–30 nm region that matched BLP's results. Considering the low energy of 5.2 J per pulse, the observed radiation in the energy range of about 120–40 eV, reference experiments and analysis of plasma gases, cryofiltration to remove contaminants, and spectra of the electrode metal, no conventional explanation was found in the prior or present work to be plausible including contaminants, electrode metal emission, and Bremsstrahlung, ion recombination, molecular or molecular ion band radiation, and instrument artifacts involving radicals and energetic ions reacting at the charge-coupled device and H2 re-radiation at the detector chamber. Moreover, predicted selective extraordinarily high-kinetic energy H was observed by the corresponding Doppler broadening of the Balmer α line.

Differential Involvement of Projection Neurons During Emergence of Spontaneous Activity in the Developing Avian Hindbrain

2009 ◽  
Vol 101 (2) ◽  
pp. 591-602 ◽  
Author(s):  
Hiraku Mochida ◽  
Gilles Fortin ◽  
Jean Champagnat ◽  
Joel C. Glover
Keyword(s):  
Spontaneous Activity ◽  
Projection Neuron ◽  
Projection Neurons ◽  
Charge Coupled Device ◽  
Neuron Populations ◽  
Motor Nerves ◽  
Differential Involvement ◽  
A Charge ◽  
The Brain ◽  
Calcium Green

To better characterize the emergence of spontaneous neuronal activity in the developing hindbrain, spontaneous activity was recorded optically from defined projection neuron populations in isolated preparations of the brain stem of the chicken embryo. Ipsilaterally projecting reticulospinal (RS) neurons and several groups of vestibuloocular (VO) neurons were labeled retrogradely with Calcium Green-1 dextran amine and spontaneous calcium transients were recorded using a charge-coupled-device camera mounted on a fluorescence microscope. Simultaneous extracellular recordings were made from one of the trigeminal motor nerves (nV) to register the occurrence of spontaneous synchronous bursts of activity. Two types of spontaneous activity were observed: synchronous events (SEs), which occurred in register with spontaneous bursts in nV once every few minutes and were tetrodotoxin (TTX) dependent, and asynchronous events (AEs), which occurred in the intervals between SEs and were TTX resistant. AEs occurred developmentally before SEs and were in general smaller and more variable in amplitude than SEs. SEs appeared at the same stage as nV bursts early on embryonic day 4, first in RS neurons and then in VO neurons. All RS neurons participated equally in SEs from the outset, whereas different subpopulations of VO neurons participated differentially, both in terms of the proportion of neurons that exhibited SEs, the fidelity with which the SEs in individual neurons followed the nV bursts, and the developmental stage at which SEs appeared and matured. The results show that spontaneous activity is expressed heterogeneously among hindbrain projection neuron populations, suggesting its differential involvement in the formation of different functional neuronal circuits.

scholarly journals A broadband cavity enhanced absorption spectrometer for aircraft measurements of glyoxal, methylglyoxal, nitrous acid, nitrogen dioxide, and water vapor

2016 ◽  
Vol 9 (2) ◽  
pp. 423-440 ◽  
Author(s):  
K.-E. Min ◽  
R. A. Washenfelder ◽  
W. P. Dubé ◽  
A. O. Langford ◽  
P. M. Edwards ◽  
...  
Keyword(s):  
Nitrogen Dioxide ◽  
Cross Sections ◽  
Nitrous Acid ◽  
Aircraft Measurements ◽  
Charge Coupled Device ◽  
Light Emitting ◽  
Enhanced Absorption ◽  
Field Campaigns ◽  
A Charge ◽  
Absorption Spectrometer

Abstract. We describe a two-channel broadband cavity enhanced absorption spectrometer (BBCEAS) for aircraft measurements of glyoxal (CHOCHO), methylglyoxal (CH3COCHO), nitrous acid (HONO), nitrogen dioxide (NO2), and water (H2O). The instrument spans 361–389 and 438–468 nm, using two light-emitting diodes (LEDs) and a single grating spectrometer with a charge-coupled device (CCD) detector. Robust performance is achieved using a custom optical mounting system, high-power LEDs with electronic on/off modulation, high-reflectivity cavity mirrors, and materials that minimize analyte surface losses. We have successfully deployed this instrument during two aircraft and two ground-based field campaigns to date. The demonstrated precision (2σ) for retrievals of CHOCHO, HONO and NO2 are 34, 350, and 80 parts per trillion (pptv) in 5 s. The accuracy is 5.8, 9.0, and 5.0 %, limited mainly by the available absorption cross sections.

Detection of Yellow Hawkweed (Hieracium pratense) with High Resolution Multispectral Digital Imagery

1995 ◽  
Vol 9 (3) ◽  
pp. 477-483 ◽  
Author(s):  
Hubert W. Carson ◽  
Lawrence W. Lass ◽  
Robert H. Callihan
Keyword(s):  
Supervised Classification ◽  
Digital Images ◽  
Ground Cover ◽  
Unsupervised Classification ◽  
Digital Imagery ◽  
Charge Coupled Device ◽  
Spectral Filters ◽  
A Charge ◽  
Northern Idaho

Yellow hawkweed infests permanent upland pastures and forest meadows in northern Idaho. Conventional surveys to determine infestations of this weed are not practical. A charge coupled device with spectral filters mounted in an airplane was used to obtain digital images (1 m resolution) of flowering yellow hawkweed. Supervised classification of the digital images predicted more area infested by yellow hawkweed than did unsupervised classification. Where yellow hawkweed was the dominant ground cover species, infestations were detectable with high accuracy from digital images. Moderate yellow hawkweed infestation detection was unreliable, and areas having less than 20% yellow hawkweed cover were not detected.

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