On the linearity of the MINOS light-injection calibration system
journal contribution
posted on 2023-06-08, 09:27authored byP Adamson, L Barrett, A Belias, A Blake, A Cabrera, Elisabeth FalkElisabeth Falk, Philip Harris, Jeff HartnellJeff Hartnell, C Howcroft, M Kordosky, K Lang, R Lee, J Liu, D Michael, R Morse, JK Nelson, R Nichol, G Pearce, K Ruddick, P N Smith, P A Symes, J Thomas, PL Vahle, R Webb, A Weber, R F White
The MINOS light-injection calibration system has been fully documented in a previous article (Nucl. Instr. and Meth. A 492 (2002) 353). Upon commissioning in the MINOS detectors, the system was found to give a non-linear response to variations in the intensity of injected light. The source of this non-linearity has been traced to a small change in the spectrum of the injected light as a function of the current applied to the original blue LEDs, in combination with a rapidly varying spectral response function of the wavelength-shifting fibre used in the detector. Both aspects of the problem have been addressed successfully by use of LEDs with different spectral characteristics, and the system now has a linear response.
History
Publication status
Published
Journal
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Two small effects conspired together to produce an unexpected nonlinearity in the MINOS LI system. I was the first to realise the source of the problem, and I (together with the small group I led) was mainly responsible for finding the solution described in this paper. I wrote the paper. Non-Sussex authors mainly carried out tests on the installed system.