Performance of Wavelength-Shifting Fibers for the Mu2e Cosmic Ray Veto Detector

The cosmic-ray-veto detector (CRV) for the Mu2e experiment consists of four layers of plastic scintillating counters read out by silicon photo-multipliers (SiPM) through wavelength-shifting fibers. This paper reports the light properties of several wavelength-shifting fiber samples with diameters of 1.0 mm, 1.4 mm, and 1.8 mm that were considered for the CRV system. A fiber diameter of 1.4 mm was selected as optimal for the CRV, and measurements of the prototype and production fiber of this diameter are presented. Fiber performance was found to exceed the CRV requirements for >99% of the spools. The measurements are performed using a scanner designed to ensure the fiber quality for the CRV.Comment: To be submitted to the Journal of Instrumentation (JINST). arXiv admin note: text overlap with arXiv:1511.0622

Performance of Wavelength-Shifting Fibers for the Mu2e Cosmic Ray Veto Detector

The Mu2e experiment will search for a neutrino-less muon-to-electron conversion process with almost four orders of magnitude of sensitivity improvement relative to the current best limit. One important background is caused by cosmic ray muons, and particles produced by their decay or interactions, mimicking the conversion electron signature. In order to reach the design sensitivity, Mu2e needs to obtain a cosmic ray veto (CRV) efficiency of 99.99\%. The CRV system consists of four layers of plastic scintillating counters read out by silicon photo-multipliers (SiPM) through wavelength shifting fibers. The CRV counters must produce sufficient photo statistics in order to achieve the required veto efficiency. We study the light properties of several wavelength shifting fiber sizes in order to optimize the total light yield for the CRV system. The measurements are performed using a scanner designed to ensure fiber quality for the CRV.Comment: 7 pages, 6 figure

Carcinogenicity of 2-Naphthylhydroxylamine and 2-Naphthylamine

THE discovery of the N-hydroxylation of 2-acetamidofluorene in vivo (Cramer, Miller and Miller, 1959) had been followed by recognition that 4-acetamidobiphenyl (Miller, Wyatt, Miller and Hartman, 1961b) and 2-naphthylamine (Boyland, Manson and Nery, 1960; Troll and Nelson, 1961) are metabolised by similar routes. The carcinogenic aromatic amines are also metabolised to ortho aminophenols, some of which have been shown to be carcinogenic by the technique of bladder pellet implantation in mice (Bonser, Bradshaw, Clayson and Jull, 1956; Allen, Boyland, Dukes, Horning and Watson, 1957), but 2-naphthylhydroxvlamine, the N-hydroxy derivative of 2-naphthylamine, has induced a higher incidence of bladder tumours than any other compound tested (Bonser, Boyland, Busby, Clayson, Grover and Jull, 1963). The N-hydroxy derivatives of 2-acetamidofluorene and 4-acetamidobiphenyl appear to be proximate carcinogens when given intraperitoneally to rats (Miller, Miller and Hartman, 1961a; Miller, Wyatt, Miller and Hartman, 1961b). The present paper describes the potent carcinogenicity of the 2-naphthylhydroxylamine in comparison with that of the parent amine following multiple intraperitoneal injections in rats. A preliminary report of this work has alread

The Induction of Renal Tumours by Feeding Lead Acetate to Rats

IN a careful examination of the long-term effects of large doses of lead, Zollinger (1953) described the tumours of the kidney in rats induced by repeated injection of lead phosphate. This finding has been confirmed by Walpole (personal communication in Matthews and Walpole, 1958) who also obtained tumours in the kidney by injection of lead phosphate. The tumours were similar to those caused by administration of 4-amino-5-fluorobiphenyl (Matthews and Walpole, 1958). Van Esch, van Genderen and Vink (1959, personal communication) fed rats on a diet containing 1 per cent of basic lead acetate over a period of two years. At the end of this period the surviving rats were killed and many were found to have malignant tumours of the kidney. That rats should survive for two years on a diet containing 1 per cent lead acetate is surprising, in view of the known toxicity of lead compounds. In this paper, the findings of van Esch, van Genderen and Vink (1959, personal communication) are confirmed. Fairhall and Miller (1941) had previously carried out experiments with much lower concentrations of lead. They maintained rats on diets containing 0.1 per cen