301 research outputs found
Optimized digital filtering techniques for radiation detection with HPGe detectors
This paper describes state-of-the-art digital filtering techniques that are
part of GEANA, an automatic data analysis software used for the GERDA
experiment. The discussed filters include a novel, nonlinear correction method
for ballistic deficits, which is combined with one of three shaping filters: a
pseudo-Gaussian, a modified trapezoidal, or a modified cusp filter. The
performance of the filters is demonstrated with a 762 g Broad Energy Germanium
(BEGe) detector, produced by Canberra, that measures {\gamma}-ray lines from
radioactive sources in an energy range between 59.5 and 2614.5 keV. At 1332.5
keV, together with the ballistic deficit correction method, all filters produce
a comparable energy resolution of ~1.61 keV FWHM. This value is superior to
those measured by the manufacturer and those found in publications with
detectors of a similar design and mass. At 59.5 keV, the modified cusp filter
without a ballistic deficit correction produced the best result, with an energy
resolution of 0.46 keV. It is observed that the loss in resolution by using a
constant shaping time over the entire energy range is small when using the
ballistic deficit correction method
A digital multi-channel spectroscopy system with 100 MHz flash ADC module for the GENIUS-TF and GENIUS projects
In this paper we will present the first results of applying a digital
processing technology in low-level gamma spectroscopy with HPGE detectors. An
experimental gamma spectrometer using Flash ADC module is built and tested. The
test system is now under development and shows major advantages over the
traditional analog technologies. It will be installed for the GENIUS-TF and
GENIUS projects in Gran-Sasso in early 2003.Comment: 8 pages, latex, 6 figures, Published in NIM, Volume 498, Issues 1-3,
Pages 334-339, also see Home Page of Heidelberg Non-Accelerator Particle
Physics Group: http://www.mpi-hd.mpg.de/non_acc
A Trigger and Readout Scheme for future Cherenkov Telescope Arrays
The next generation of ground-based gamma-ray observatories, such as e.g.
CTA, will consist of about 50-100 telescopes, and cameras with in total ~100000
to ~200000 channels. The telescopes of the core array will cover and effective
area of ~ 1 km2 and will be possibly accompanied by a large halo of smaller
telescopes spread over about 10 km2 . In order to make maximum use of the
stereoscopic approach, a very flexible inter-telescope trigger scheme is needed
which allows to couple telescopes that located up to ~1 km apart. The
development of a cost effective readout scheme for the camera signals exhibits
a major technological challenge. Here we present ideas on a new asynchronous
inter-telescope trigger scheme, and a very cost-effective, high-bandwidth
frontend to backend data transfer system, both based on standard Ethernet
components and an Ethernet front-end interface based on mass production
standard FPGAs.Comment: 4 pages, 3 figures ; modified version of article to be published in
the proceedings of the "4th Heidelberg International Symposium on High Energy
Gamma-Ray Astronomy 2008
FlashCam: A fully digital camera for CTA telescopes
The future Cherenkov Telescope Array (CTA) will consist of several tens of
telescopes of different mirror sizes. CTA will provide next generation
sensitivity to very high energy photons from few tens of GeV to >100 TeV.
Several focal plane instrumentation options are currently being evaluated
inside the CTA consortium. In this paper, the current status of the FlashCam
prototyping project is described. FlashCam is based on a fully digital camera
readout concept and features a clean separation between photon detector plane
and signal digitization/triggering electronics.Comment: In Proceedings of the 2012 Heidelberg Symposium on High Energy
Gamma-Ray Astronomy. All CTA contributions at arXiv:1211.184
Performance Verification of the FlashCam Prototype Camera for the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) is a future gamma-ray observatory that is
planned to significantly improve upon the sensitivity and precision of the
current generation of Cherenkov telescopes. The observatory will consist of
several dozens of telescopes with different sizes and equipped with different
types of cameras. Of these, the FlashCam camera system is the first to
implement a fully digital signal processing chain which allows for a traceable,
configurable trigger scheme and flexible signal reconstruction. As of autumn
2016, a prototype FlashCam camera for the medium-sized telescopes of CTA nears
completion. First results of the ongoing system tests demonstrate that the
signal chain and the readout system surpass CTA requirements. The stability of
the system is shown using long-term temperature cycling.Comment: 5 pages, 13 figures, Proceedings of the 9th International Workshop on
Ring Imaging Cherenkov Detectors (RICH 2016), Lake Bled, Sloveni
FlashCam: a fully-digital camera for the medium-sized telescopes of the Cherenkov Telescope Array
The FlashCam group is currently preparing photomultiplier-tube based cameras
proposed for the medium-sized telescopes (MST) of the Cherenkov Telescope Array
(CTA). The cameras are designed around the FlashCam readout concept which is
the first fully-digital readout system for Cherenkov cameras, based on
commercial FADCs and FPGAs as key components for the front-end electronics
modules and a high performance camera server as back-end. This contribution
describes the progress of the full-scale FlashCam camera prototype currently
under construction, as well as performance results also obtained with earlier
demonstrator setups. Plans towards the production and implementation of
FlashCams on site are also briefly presented.Comment: 8 pages, 6 figures. In Proceedings of the 34th International Cosmic
Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions
at arXiv:1508.0589
Progress in Monte Carlo design and optimization of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) will be an instrument covering a wide
energy range in very-high-energy (VHE) gamma rays. CTA will include several
types of telescopes, in order to optimize the performance over the whole energy
range. Both large-scale Monte Carlo (MC) simulations of CTA super-sets
(including many different possible CTA layouts as sub-sets) and smaller-scale
simulations dedicated to individual aspects were carried out and are on-going.
We summarize results of the prior round of large-scale simulations, show where
the design has now evolved beyond the conservative assumptions of the prior
round and present first results from the on-going new round of MC simulations.Comment: 4 pages, 5 figures. In Proceedings of the 33rd International Cosmic
Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at
arXiv:1307.223
A giant stem-group chaetognath.
Chaetognaths, with their characteristic grasping spines, are the oldest known pelagic predators, found in the lowest Cambrian (Terreneuvian). Here, we describe a large stem chaetognath, gen. et sp. nov., from the lower Cambrian Sirius Passet Lagerstätte, which exhibits lateral and caudal fins, a distinct head region with long antennae and a jaw apparatus similar to . has previously been interpreted as a total-group chaetognathiferan, as either a stem-chaetognath or gnathostomulid. We show that shares a ventral ganglion with chaetognaths to the exclusion of other animal groups, firmly placing these fossils on the chaetognath stem. The large size (up to 30 cm) and gut contents in suggest that early chaetognaths occupied a higher trophic position in pelagic food chains than today
Background free search for neutrinoless double beta decay with GERDA Phase II
The Standard Model of particle physics cannot explain the dominance of matter
over anti-matter in our Universe. In many model extensions this is a very
natural consequence of neutrinos being their own anti-particles (Majorana
particles) which implies that a lepton number violating radioactive decay named
neutrinoless double beta () decay should exist. The detection
of this extremely rare hypothetical process requires utmost suppression of any
kind of backgrounds.
The GERDA collaboration searches for decay of Ge
(^{76}\rm{Ge} \rightarrow\,^{76}\rm{Se} + 2e^-) by operating bare detectors
made from germanium with enriched Ge fraction in liquid argon. Here, we
report on first data of GERDA Phase II. A background level of
cts/(keVkgyr) has been achieved which is the world-best if
weighted by the narrow energy-signal region of germanium detectors. Combining
Phase I and II data we find no signal and deduce a new lower limit for the
half-life of yr at 90 % C.L. Our sensitivity of
yr is competitive with the one of experiments with
significantly larger isotope mass.
GERDA is the first experiment that will be background-free
up to its design exposure. This progress relies on a novel active veto system,
the superior germanium detector energy resolution and the improved background
recognition of our new detectors. The unique discovery potential of an
essentially background-free search for decay motivates a
larger germanium experiment with higher sensitivity.Comment: 14 pages, 9 figures, 1 table; ; data, figures and images available at
http://www.mpi-hd.mpg/gerda/publi
- …