Abstract
In this paper we outline an experiment to detect the conversion of photons to axion-like particles (ALPs) in a strong magnetic field. We show that by modulating the polarization of the light ...passing through a Fabry-Perot cavity so that it effectively precesses at the modulation frequency, a signal is produced that is proportional to the square, as opposed to the fourth power, of the ALP-photon coupling constant. Assuming shot noise to be the dominant source of noise, we estimate that this approach is sensitive to ALP masses less than 10
-4
eV and couplings on the order to
g
aγ
> 1.6 × 10
-11
GeV
-1
with a 10 m, 10 T magnet, and
g
aγ
> 1.6 × 10
-12
GeV
-1
with a 100 m magnet as envisaged by ALPs-IIc. ALPs with these properties have been invoked to explain the apparent transparency of the extragalactic background light (EBL) to ultra high-energy gamma rays emitted by BLAZARs.
We report the results of a search for neutrinoless double-beta decay in a 9.8 kg yr exposure of Te-130 using a bolometric detector array, CUORE-0. The characteristic detector energy resolution and ...background level in the region of interest are 5.1 +/- 0.3 keV FWHM and 0.058 +/- 0.004(stat) +/- 0.002(syst)counts/(keV kg yr), respectively. The median 90% C.L. lower-limit half-life sensitivity of the experiment is 2.9 x 10(24) yr and surpasses the sensitivity of previous searches. We find no evidence for neutrinoless double-beta decay of Te-130 and place a Bayesian lower bound on the decay half-life, T-1/2(0 nu) > 2.7 x 10(24) yr at 90% C.L. Combining CUORE-0 data with the 19.75 kg yr exposure of Te-130 from the Cuoricino experiment we obtain T-1/2(0 nu) > 4.0 x 10(24) yr at 90% C.L. (Bayesian), the most stringent limit to date on this half-life. Using a range of nuclear matrix element estimates we interpret this as a limit on the effective Majorana neutrino mass, m beta beta < 270-760 meV.
We describe in detail the methods used to obtain the lower bound on the lifetime of neutrinoless double-beta (0 nu beta beta) decay in Te-130 and the associated limit on the effective Majorana mass ...of the neutrino using the CUORE-0 detector. CUORE-0 is a bolometric detector array located at the Laboratori Nazionali del Gran Sasso that was designed to validate the background reduction techniques developed for CUORE, a next-generation experiment scheduled to come online in 2016. CUORE-0 is also a competitive 0 nu beta beta decay search in its own right and functions as a platform to further develop the analysis tools and procedures to be used in CUORE. These include data collection, event selection and processing, as well as an evaluation of signal efficiency. In particular, we describe the amplitude evaluation, thermal gain stabilization, energy calibration methods, and the analysis event selection used to create our final 0 nu beta beta search spectrum. We define our high level analysis procedures, with emphasis on the new insights gained and challenges encountered. We outline in detail our fitting methods near the hypothesized 0 nu beta beta decay peak and catalog the main sources of systematic uncertainty. Finally, we derive the 0 nu beta beta decay half-life limits previously reported for CUORE-0, T-1/2(0 nu) > 2.7 x 10(24) yr, and in combination with the Cuoricino limit, T-1/2(0 nu) > 4.0 x 10(24) yr.
Axions can be considered as good dark matter candidates. The detection of such light particles can be achieved by observing axion-induced atomic excitations. The target is in a magnetic field so that ...the m-degeneracy is removed, and the energy levels can be suitably adjusted. Using an axion-electron coupling indicated by the limit obtained by the Borexino experiment, which is quite stringent, reasonable axion absorption rates have been obtained for various atomic targets The obtained results depend, of course, on the atom considered through the parameters ϵ (the spin−orbit splitting) as well as δ ( the energy splitting due to the magnetic moment interaction). This assumption allows axion masses in the tens of μeV if the transition occurs between members of the same multiplet, i.e., |J1,M1=−J1⟩→|J1,M1=−J+1⟩,J1≠0, and axion masses in the range 1 meV–1 eV for transitions of the spin−orbit splitting type |J1,M=−J1⟩→|J2,M2=−J1+q⟩,q=−1,0,1, i.e., three types of transition. The axion mass that can be detected is very close to the excitation energy involved, which can vary by adjusting the magnetic field. Furthermore, since the axion is absorbed by the atom, the calculated cross-section exhibits the behavior of a resonance, which can be exploited by experiments to minimize any background events.
CUORE: a cryogenic underground observatory for rare events Arnaboldi, C; Avignone III, F.T; Beeman, J ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
3
Journal Article
Recenzirano
Odprti dostop
CUORE is a proposed tightly packed array of 1000 TeO
2 bolometers, each being a cube
5
cm
on a side with a mass of
760
g
. The array consists of 25 vertical towers, arranged in a square of 5 towers×5 ...towers, each containing 10 layers of four crystals. The design of the detector is optimized for ultralow-background searches: for neutrinoless double-beta decay of
130
Te
(33.8% abundance), cold dark matter, solar axions, and rare nuclear decays. A preliminary experiment involving 20 crystals
3×3×6
cm
3
of
340
g
has been completed, and a single CUORE tower is being constructed as a smaller-scale experiment called CUORICINO. The expected performance and sensitivity, based on Monte Carlo simulations and extrapolations of present results, are reported.
Initial performance of the CUORE-0 experiment Artusa, D. R.; Avignone, F. T.; Azzolini, O. ...
The European physical journal. C, Particles and fields,
08/2014, Letnik:
74, Številka:
8
Journal Article
Recenzirano
Odprti dostop
CUORE-0 is a cryogenic detector that uses an array of tellurium dioxide bolometers to search for neutrinoless double-beta decay of
130
Te
. We present the first data analysis with
7.1
kg
·
y
of total
...TeO
2
exposure focusing on background measurements and energy resolution. The background rates in the neutrinoless double-beta decay region of interest (2.47 to
2.57
MeV
) and in the
α
background-dominated region (2.70 to
3.90
MeV
) have been measured to be
0.071
±
0.011
and
0.019
±
0.002
counts
/
(
keV
·
kg
·
y
)
, respectively. The latter result represents a factor of 6 improvement from a predecessor experiment, Cuoricino. The results verify our understanding of the background sources in CUORE-0, which is the basis of extrapolations to the full CUORE detector. The obtained energy resolution (full width at half maximum) in the region of interest is
5.7
keV
. Based on the measured background rate and energy resolution in the region of interest, CUORE-0 half-life sensitivity is expected to surpass the observed lower bound of Cuoricino with one year of live time.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We consider possible experimental tests of recent hypotheses suggesting that TeV photons survive the pair production interaction with extragalactic background light over cosmological distances by ...converting to axion-like particles (ALPs) in galactic magnetic fields. We show that proposed giant ultra-low background scintillation detectors will even have a difficult time reaching the present CAST sensitivity, which is one to two orders of magnitude less sensitive than necessary for a meaningful test of the ALP-photon oscillation hypothesis. Potential alternative tests are briefly discussed.
PDF
