2,015 research outputs found
Search for Neutrinoless Double Beta Decay with NEMO 3 and SuperNEMO
Since 2003 the NEMO~3 experiment has been searching for neutrinoless double
beta decay using about 10 kg of enriched isotopes. A limit of T_(1/2)(0nu) >
5.8 10**23 years at 90 % CL has been obtained for 100-Mo from the first two
years of data. Several measurements of two-neutrino double beta decays have
also been performed. A first NEMO 3 measurement of the half-life of 130-Te is
presented, giving a value of T_(1/2)(2nu) = (7.6 +- 1.5 (stat) +- 0.8 (syst))
10**20 years. In parallel, there is an active R&D programme for the SuperNEMO
experiment which is expected to commence data taking in 2012-2013 with 100-200
kg of enriched isotopes.Comment: 6 pages, 3 figures, Proceedings of the 2007 Europhysics Conference on
High Energy Physics, in Manchester, England, 19-25 July 200
Introduction to quantum optimal control for quantum sensing with nitrogen-vacancy centers in diamond
Diamond based quantum technology is a fast emerging field with both scientific and technological importance. With the growing knowledge and experience concerning diamond based quantum systems comes an increased demand for performance. Quantum optimal control (QOC) provides a direct solution to a number of existing challenges as well as a basis for proposed future applications. Together with a swift review of QOC strategies, quantum sensing, and other relevant quantum technology applications of nitrogen-vacancy (NV) centers in diamond, the authors give the necessary background to summarize recent advancements in the field of QOC assisted quantum applications with NV centers in diamond
Robust magnetometry with single nitrogen-vacancy centers via two-step optimization
Shallow nitrogen-vacancy (NV) centers are promising candidates for high-precision sensing applications; these defects, when positioned a few nanometers below the surface, provide an atomic-scale resolution along with substantial sensitivity. However, the dangling bonds and impurities on the diamond surface result in a complex environment which reduces the sensitivity and is unique to each shallow NV center. To avoid the environment's detrimental effect, we apply feedback-based quantum optimal control. We first show how a direct search can improve the initialization and readout process. In a second step, we optimize microwave pulses for pulsed optically detected magnetic resonance (ODMR) and Ramsey measurements. Throughout the sensitivity optimizations, we focus on robustness against errors in the control field amplitude. This feature not only protects the protocols' sensitivity from drifts but also enlarges the sensing volume. The resulting ODMR measurements produce sensitivities below 1μT Hz-12 for an 83% decrease in control power, increasing the robustness by approximately one third. The optimized Ramsey measurements produce sensitivities below 100 nT Hz-12 giving a twofold sensitivity improvement. Being on par with typical sensitivities obtained via single NV magnetometry, the complementing robustness of the presented optimization strategy may provide an advantage for other NV-based applications
The first 62 AGN observed with SDSS-IV MaNGA -- III: stellar and gas kinematics
We investigate the effects of Active Galactic Nuclei (AGN) on the gas
kinematics of their host galaxies, using MaNGA data for a sample of 62 AGN
hosts and 109 control galaxies (inactive galaxies). We compare orientation of
the line of nodes (kinematic Position Angle - PA) measured from the gas and
stellar velocity fields for the two samples. We found that AGN hosts and
control galaxies display similar kinematic PA offsets between gas and stars.
However, we note that AGN have larger fractional velocity dispersion
differences between gas and stars [] when compared to their controls, as
obtained from the velocity dispersion values of the central (nuclear) pixel
(2.5" diameter). The AGN have a median value of of
, while the the median value for the control
galaxies is . 75% of the AGN show
, while 75% of the normal galaxies show , thus we suggest that the parameter can be
used as an indicative of AGN activity. We find a correlation between the
[OIII]5007 luminosity and for our sample. Our main
conclusion is that the AGN already observed with MaNGA are not powerful enough
to produce important outflows at galactic scales, but at 1-2 kpc scales, AGN
feedback signatures are always present on their host galaxies.Comment: 19 pages, 8 figures, published in MNRA
SSDSS IV MaNGA - Properties of AGN host galaxies
We present here the characterization of the main properties of a sample of 98
AGN host galaxies, both type-II and type-I, in comparison with those of about
2700 non-active galaxies observed by the MaNGA survey. We found that AGN hosts
are morphologically early-type or early-spirals. For a given morphology AGN
hosts are, in average, more massive, more compact, more central peaked and
rather pressurethan rotational-supported systems. We confirm previous results
indicating that AGN hosts are located in the intermediate/transition region
between star-forming and non-star-forming galaxies (i.e., the so-called green
valley), both in the ColorMagnitude and the star formation main sequence
diagrams. Taking into account their relative distribution in terms of the
stellar metallicity and oxygen gas abundance and a rough estimation of their
molecular gas content, we consider that these galaxies are in the process of
halting/quenching the star formation, in an actual transition between both
groups. The analysis of the radial distributions of the starformation rate,
specific star-formation rate, and molecular gas density shows that the
quenching happens from inside-out involving both a decrease of the efficiency
of the star formation and a deficit of molecular gas. All the intermediate
data-products used to derive the results of our analysis are distributed in a
database including the spatial distribution and average properties of the
stellar populations and ionized gas, published as a Sloan Digital Sky Survey
Value Added Catalog being part of the 14th Data Release:
http://www.sdss.org/dr14/manga/manga-data/manga-pipe3d-value-added-catalog/Comment: 48 pages, 14 figures, in press in RMxA
Active galactic nuclei signatures in Red Geyser galaxies from Gemini GMOS-IFU observations
Red Geysers are quiescent galaxies with galactic scale ionized outflows, likely due to low-luminosity active galactic nuclei (AGN). We used Gemini GMOS-IFU observations of the inner~1–3 kpc of nine Red Geysers selected from the MaNGA survey to study the gas ionization and kinematics. The emission-line ratios suggest the presence of Seyfert/LINER (Low Ionization Nuclear Emission Region) nuclei in all sources. Two galaxies show Hα equivalent width ( Hα EW) larger than 3 Å (indicative of AGN ionization) within an aperture 2 . 5 of diameter (1.3–3.7 kpc at the distance of galaxies) for MaNGA data, while with the higher resolution GMOS data, four galaxies present Hα EW>3 Å within an aperture equal to the angular resolution (0.3–0.9 kpc). For two objects with GMOS-IFU data, the Hα EW is lower than 3 Å but larger than 1.5 Å, most probably due to a faint AGN. The spatially resolved electron density maps show values between 100 and 3000 cm −3 and are consistent with those determined in other studies. The large (MaNGA) and the nuclear scale (GMOS-IFU) gas velocity fields are misaligned, with a kinematic position angle difference between 12◦ and 60◦. The [N II] λ6583 emission-line profiles are asymmetrical, with blue wings on the redshifted side of the velocity field and red wings on the blueshifted side. Our results support previous indications that the gas in Red Geysers is ionized by an AGN, at least in their central region, with the presence of outflows, likely originating in a precessing accretion disc
Gas phase metallicity determinations in nearby AGNs with SDSS-IV MaNGA: evidence of metal poor accretion
We derive the metallicity (traced by the O/H abundance) of the Narrow Line
Region ( NLR) of 108 Seyfert galaxies as well as radial metallicity gradients
along their galaxy disks and of these of a matched control sample of no active
galaxies. In view of that, observational data from the SDSS-IV MaNGA survey and
strong emission-line calibrations taken from the literature were considered.
The metallicity obtained for the NLRs %each Active Galactic Nucleus (AGN) was
compared to the value derived from the extrapolation of the radial oxygen
abundance gradient, obtained from \ion{H}{ii} region estimates along the galaxy
disk, to the central part of the host galaxies. We find that, for most of the
objects (), the NLR metallicity is lower than the extrapolated
value, with the average difference ( is due to the accretion of metal-poor
gas to the AGN that feeds the nuclear supermassive black hole (SMBH), which is
drawn from a reservoir molecular and/or neutral hydrogen around the SMBH.
Additionally, we look for correlations between and the electron density
(), [\ion{O}{iii}]5007 and H luminosities,
extinction coefficient ( of the NLRs, as well as the stellar mass
() of the host galaxies. Evidences of an inverse correlation between the
and the parameters , and were found
Higgs boson production in photon-photon collision at ILC: a comparative study in different little Higgs models
We study the process \gamma\gamma->h->bb_bar at ILC as a probe of different
little Higgs models, including the simplest little Higgs model (SLH), the
littlest Higgs model (LH), and two types of littlest Higgs models with T-parity
(LHT-I, LHT-II). Compared with the Standard Model (SM) prediction, the
production rate is found to be sizably altered in these little Higgs models
and, more interestingly, different models give different predictions. We find
that the production rate can be possibly enhanced only in the LHT-II for some
part of the parameter space, while in all other cases the rate is suppressed.
The suppression can be 10% in the LH and as much as 60% in both the SLH and the
LHT-I/LHT-II. The severe suppression in the SLH happens for a large \tan\beta
and a small m_h, in which the new decay mode h->\eta\eta (\eta is a light
pseudo-scalar) is dominant; while for the LHT-I/LHT-II the large suppression
occurs when f and m_h are both small so that the new decay mode h->A_H A_H is
dominant. Therefore, the precision measurement of such a production process at
the ILC will allow for a test of these models and even distinguish between
different scenarios.Comment: Version in JHEP (h-g-g & h-gamma-gamma expressions added
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