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Measurement of Na and I recoil discrimination and detection efficiency in a cooled ‘UVIS’ NaI crystal for dark matter searches |
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| Authors: | N. J. C. Spooner G. J. Davies C. H. Lally N. J. T. Smith M. van den Putte P. F. Smith J. D. Lewin G. T. A. Squier P. Jagpal |
| Affiliation: | a Department of Physics, The Hicks Building, University of Sheffield Sheffield, S3 7RH UK b Imperial College, Blackett Laboratory, Prince Consort Rd. London, SW7 2BZ UK c Rutherford Appleton Laboratory, Chilton Oxon., OX11 0QX UK d Physics Department, University of Birmingham, Edgbaston Birmingham, B15 2TT UK |
| Abstract: | The UVIS dark matter detector, proposed by Spooner and Smith (Phys. Lett. B 314 (1993) 430), consists of < 1000 ppm Tl doped NaI scintillator operated at 100-200 K, with measurement of UV and visible scintillation components used to discriminate between electrons (gammas) and Na or I recoils. Presented here are results of measurements of the gamma/nuclear recoil discrimination power of a Kyropolous NaI (0.5 ppm Tl) UVIS test detector operated at 160 K, with monoenergetic neutrons used to induce nuclear recoils via elastic scattering. Defining the statistical gain factor for N events as , the coefficient Cm was measured as a function of photoelectron pulse height. At 40 photoelectrons Cm was found to be 0.5 (corresponding to 90% rejection of gammas with 20% loss of neutron events). The scintillation efficiency for Na and I recoils relative to electrons was also measured at 160 K and found to be 35 ± 5% for Na recoils and 10 ± 2% for iodine. |
| Keywords: | WIMPS Neutralino Low background |
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