197 research outputs found
Radon and material radiopurity assessment for the NEXT double beta decay experiment
The Neutrino Experiment with a Xenon TPC (NEXT), intended to investigate the
neutrinoless double beta decay using a high-pressure xenon gas TPC filled with
Xe enriched in 136Xe at the Canfranc Underground Laboratory in Spain, requires
ultra-low background conditions demanding an exhaustive control of material
radiopurity and environmental radon levels. An extensive material screening
process is underway for several years based mainly on gamma-ray spectroscopy
using ultra-low background germanium detectors in Canfranc but also on mass
spectrometry techniques like GDMS and ICPMS. Components from shielding,
pressure vessel, electroluminescence and high voltage elements and energy and
tracking readout planes have been analyzed, helping in the final design of the
experiment and in the construction of the background model. The latest
measurements carried out will be presented and the implication on NEXT of their
results will be discussed. The commissioning of the NEW detector, as a first
step towards NEXT, has started in Canfranc; in-situ measurements of airborne
radon levels were taken there to optimize the system for radon mitigation and
will be shown too.Comment: Proceedings of the Low Radioactivity Techniques 2015 workshop
(LRT2015), Seattle, March 201
Measurement of radon-induced backgrounds in the NEXT double beta decay experiment
The measurement of the internal Rn activity in the NEXT-White
detector during the so-called Run-II period with Xe-depleted xenon is
discussed in detail, together with its implications for double beta decay
searches in NEXT. The activity is measured through the alpha production rate
induced in the fiducial volume by Rn and its alpha-emitting progeny.
The specific activity is measured to be ~mBq/m. Radon-induced electrons have also been
characterized from the decay of the Bi daughter ions plating out on the
cathode of the time projection chamber. From our studies, we conclude that
radon-induced backgrounds are sufficiently low to enable a successful NEXT-100
physics program, as the projected rate contribution should not exceed
0.1~counts/yr in the neutrinoless double beta decay sample.Comment: 28 pages, 10 figures, 6 tables. Version accepted for publication in
JHE
NEXT-100 Technical Design Report (TDR). Executive Summary
In this Technical Design Report (TDR) we describe the NEXT-100 detector that
will search for neutrinoless double beta decay (bbonu) in Xe-136 at the
Laboratorio Subterraneo de Canfranc (LSC), in Spain. The document formalizes
the design presented in our Conceptual Design Report (CDR): an
electroluminescence time projection chamber, with separate readout planes for
calorimetry and tracking, located, respectively, behind cathode and anode. The
detector is designed to hold a maximum of about 150 kg of xenon at 15 bar, or
100 kg at 10 bar. This option builds in the capability to increase the total
isotope mass by 50% while keeping the operating pressure at a manageable level.
The readout plane performing the energy measurement is composed of Hamamatsu
R11410-10 photomultipliers, specially designed for operation in low-background,
xenon-based detectors. Each individual PMT will be isolated from the gas by an
individual, pressure resistant enclosure and will be coupled to the sensitive
volume through a sapphire window. The tracking plane consists in an array of
Hamamatsu S10362-11-050P MPPCs used as tracking pixels. They will be arranged
in square boards holding 64 sensors (8 times8) with a 1-cm pitch. The inner
walls of the TPC, the sapphire windows and the boards holding the MPPCs will be
coated with tetraphenyl butadiene (TPB), a wavelength shifter, to improve the
light collection.Comment: 32 pages, 22 figures, 5 table
- …