224 research outputs found
Benchmarking TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems
Scintillation light from liquid argon is produced at 128 nm and thus must be shifted to visible wavelengths in light detection systems used for Liquid Argon Time Projection Chambers (LArTPCs). To date, designs have employed tetraphenyl butadiene (TPB) coatings on photomultiplier tubes (PMTs) or plates placed in front of the PMTs. Recently, a new approach using TPB-coated light guides was proposed. In this paper, we show that the response of lightguides coated with TPB in a UV Transmitting (UVT) acrylic matrix is very similar to that of a coating using a polystyrene (PS) matrix. We obtain a factor of three higher light yield than has been previously reported from lightguides. This paper provides information on the response of the lightguides so that these can be modeled in simulations for future LArTPCs. This paper also identifies areas of R&D for potential improvements in the lightguide respons
On two weak CC Delta production models
We perform a detail analysis of two models of neutrino CC Delta production on
free nucleons. First model is a standard one based on nucleon-Delta transition
current with several form-factors. Second model is a starting point for a
construction of Marteau model with sophisticated analytical computations of
nuclear effects. We conclude that both models lead to similar results.Comment: 9 pages, includes 9 figures, accepted for publication in J. Phys.
New Measurements of Nucleon Structure Functions from the CCFR/NuTeV Collaboration
We report on the extraction of the structure functions F_2 and Delta xF_3 =
xF_3nu-xF_3nubar from CCFR neutrino-Fe and antineutrino-Fe differential cross
sections. The extraction is performed in a physics model independent (PMI) way.
This first measurement for Delta xF_3, which is useful in testing models of
heavy charm production, is higher than current theoretical predictions. The F_2
(PMI) values measured in neutrino and muon scattering are in good agreement
with the predictions of Next to Leading Order PDFs (using massive charm
production schemes), thus resolving the long-standing discrepancy between the
two sets of data.Comment: 5 pages. Presented by Arie Bodek at the CIPNAP2000 Conference, Quebec
City, May 200
Environmental Effects on TPB Wavelength-Shifting Coatings
The scintillation detection systems of liquid argon time projection chambers
(LArTPCs) require wavelength shifters to detect the 128 nm scintillation light
produced in liquid argon. Tetraphenyl butadiene (TPB) is a fluorescent material
that can shift this light to a wavelength of 425 nm, lending itself well to use
in these detectors. We can coat the glass of photomultiplier tubes (PMTs) with
TPB or place TPB-coated plates in front of the PMTs.
In this paper, we investigate the degradation of a chemical TPB coating in a
laboratory or factory environment to assess the viability of long-term TPB film
storage prior to its initial installation in an LArTPC. We present evidence for
severe degradation due to common fluorescent lights and ambient sunlight in
laboratories, with potential losses at the 40% level in the first day and
eventual losses at the 80% level after a month of exposure. We determine the
degradation is due to wavelengths in the UV spectrum, and we demonstrate
mitigating methods for retrofitting lab and factory environments
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