14 research outputs found
Biomechanical modulation of collagen fragment-induced anabolic and catabolic activities in chondrocyte/agarose constructs
The present study examined the effect of collagen fragments on anabolic and catabolic activities by chondrocyte/agarose constructs subjected to dynamic compression..
Background due to stored electrons following nuclear decays in the KATRIN spectrometers and its impact on the neutrino mass sensitivity
The KATRIN experiment is designed to measure the absolute neutrino mass scale
with a sensitivity of 200 meV at 90% C.L. by high resolution tritium
beta-spectroscopy. A low background level of 10 mHz at the beta-decay endpoint
is required in order to achieve the design sensitivity. In this paper we
discuss a novel background source arising from magnetically trapped keV
electrons in electrostatic retarding spectrometers. The main sources of these
electrons are alpha-decays of the radon isotopes (219,220)Rn as well as
beta-decays of tritium in the volume of the spectrometers. We characterize the
expected background signal by extensive MC simulations and investigate the
impact on the KATRIN neutrino mass sensitivity. From these results we refine
design parameters for the spectrometer vacuum system and propose active
background reduction methods to meet the stringent design limits for the
overall background rate
Commissioning of the vacuum system of the KATRIN Main Spectrometer
The KATRIN experiment will probe the neutrino mass by measuring the
beta-electron energy spectrum near the endpoint of tritium beta-decay. An
integral energy analysis will be performed by an electro-static spectrometer
(Main Spectrometer), an ultra-high vacuum vessel with a length of 23.2 m, a
volume of 1240 m^3, and a complex inner electrode system with about 120000
individual parts. The strong magnetic field that guides the beta-electrons is
provided by super-conducting solenoids at both ends of the spectrometer. Its
influence on turbo-molecular pumps and vacuum gauges had to be considered. A
system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter
strips has been deployed and was tested during the commissioning of the
spectrometer. In this paper the configuration, the commissioning with bake-out
at 300{\deg}C, and the performance of this system are presented in detail. The
vacuum system has to maintain a pressure in the 10^{-11} mbar range. It is
demonstrated that the performance of the system is already close to these
stringent functional requirements for the KATRIN experiment, which will start
at the end of 2016.Comment: submitted for publication in JINST, 39 pages, 15 figure
Commissioning of the vacuum system of the KATRIN Main Spectrometer
The KATRIN experiment will probe the neutrino mass by measuring the -electron
energy spectrum near the endpoint of tritium -decay. An integral energy analysis will be performed
by an electro-static spectrometer (“Main Spectrometer”), an ultra-high vacuum vessel with a length
of 23.2 m, a volume of 1240m3, and a complex inner electrode system with about 120 000 individual
parts. The strong magnetic field that guides the -electrons is provided by super-conducting
solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum
gauges had to be considered. A system consisting of 6 turbo-molecular pumps and 3 km of
non-evaporable getter strips has been deployed and was tested during the commissioning of the
spectrometer. In this paper the configuration, the commissioning with bake-out at 300 C, and the
performance of this system are presented in detail. The vacuum system has to maintain a pressure in
the 10 mbar range. It is demonstrated that the performance of the system is already close to these
stringent functional requirements for the KATRIN experiment, which will start at the end of 2016