Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userModeling of GERDA Phase II data
66
0
0.0
(
0
)
Added by
Katharina von Sturm
Publication date
2019
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
The GERmanium Detector Array (GERDA) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta ($0 ubetabeta$) decay of $^{76}$Ge. The technological challenge of GERDA is to operate in a background-free regime in the region of interest (ROI) after analysis cuts for the full 100$,$kg$cdot$yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around $Q_{betabeta}$ for the $0 ubetabeta$ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos ($2 ubetabeta$) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for GERDA Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of $16.04^{+0.78}_{-0.85} cdot 10^{-3},$cts/(kg$cdot$keV$cdot$yr) for the enriched BEGe data set and $14.68^{+0.47}_{-0.52} cdot 10^{-3},$cts/(kg$cdot$keV$cdot$yr) for the enriched coaxial data set. These values are similar to the one of Gerda Phase I despite a much larger number of detectors and hence radioactive hardware components.
rate research
Read More
The GERDA experiment searches for the lepton number violating neutrinoless double beta decay of $^{76}$Ge ($^{76}$Ge $rightarrow$ $^{76}$Se + 2e$^-$) operating bare Ge diodes with an enriched $^{76}$Ge fraction in liquid argon. The exposure for BEGe-type detectors is increased threefold with respect to our previous data release. The BEGe detectors feature an excellent background suppression from the analysis of the time profile of the detector signals. In the analysis window a background level of $1.0_{-0.4}^{+0.6}cdot10^{-3}$ cts/(keV$cdot$kg$cdot$yr) has been achieved; if normalized to the energy resolution this is the lowest ever achieved in any 0$ ubetabeta$ experiment. No signal is observed and a new 90 % C.L. lower limit for the half-life of $8.0cdot10^{25}$ yr is placed when combining with our previous data. The median expected sensitivity assuming no signal is $5.8cdot10^{25}$ yr.
A search for neutrinoless $betabeta$ decay processes accompanied with Majoron emission has been performed using data collected during Phase I of the GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso of INFN (Italy). Processes with spectral indices n = 1, 2, 3, 7 were searched for. No signals were found and lower limits of the order of 10$^{23}$ yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with $^{76}$Ge. A new result for the half-life of the neutrino-accompanied $betabeta$ decay of $^{76}$Ge with significantly reduced uncertainties is also given, resulting in $T^{2 u}_{1/2} = (1.926 pm 0.095)cdot10^{21}$ yr.
The Gerda experiment designed to search for the neutrinoless double beta decay in 76Ge has successfully completed the first data collection. No signal excess is found, and a lower limit on the half life of the process is set, with T1/2 > 2.1x10^25 yr (90% CL). After a review of the experimental setup and of the main Phase I results, the hardware upgrade for Gerda Phase II is described, and the physics reach of the new data collection is reported.
The GERmanium Detector Array (GERDA) experiment located at the INFN Gran Sasso Laboratory (Italy), is looking for the neutrinoless double beta decay of Ge76, by using high-purity germanium detectors made from isotopically enriched material. The combination of the novel experimental design, the careful material selection for radio-purity and the active/passive shielding techniques result in a very low residual background at the Q-value of the decay, about 1e-3 counts/(keV kg yr). This makes GERDA the first experiment in the field to be background-free for the complete design exposure of 100 kg yr. A search for neutrinoless double beta decay was performed with a total exposure of 47.7 kg yr: 23.2 kg yr come from the second phase (Phase II) of the experiment, in which the background is reduced by about a factor of ten with respect to the previous phase. The analysis presented in this paper includes 12.4 kg yr of new Phase II data. No evidence for a possible signal is found: the lower limit for the half-life of Ge76 is 8.0e25 yr at 90% CL. The experimental median sensitivity is 5.8e25 yr. The experiment is currently taking data. As it is running in a background-free regime, its sensitivity grows linearly with exposure and it is expected to surpass 1e26 yr within 2018.
Identifying the nature and origin of dark matter is one of the major challenges for modern astro and particle physics. Direct dark-matter searches aim at an observation of dark-matter particles interacting within detectors. The focus of several such searches is on interactions with nuclei as provided e.g. by Weakly Interacting Massive Particles. However, there is a variety of dark-matter candidates favoring interactions with electrons rather than with nuclei. One example are dark photons, i.e., long-lived vector particles with a kinetic mixing to standard-model photons. In this work we present constraints on this kinetic mixing based on data from CRESST-II Phase 2 corresponding to an exposure before cuts of 52,kg-days. These constraints improve the existing ones for dark-photon masses between 0.3 and 0.7,keV/c$^2$.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
