The DEAP-3600 experiment, located at SNOLAB, is searching for dark matter with a single phase liquid argon (LAr) target. For a background-free exposure of 3000 kg·yr, the projected sensitivity to the ...spin-independent WIMP-nucleon cross section at 100 GeV/c2 WIMP mass is 10−46 cm2. The experimental signature of dark matter interactions is keV-scale argon recoils producing 128 nm LAr scintillation photons which are wavelength shifted and observed by 255 PMTs. To reach the large background-free exposure, a combination of careful material selection, passive shielding, active vetoes, fiducialization and pulse shape discrimination (PSD) is used. The main concept of the background rejection in DEAP-3600 is the powerful PSD, employing the large difference between fast and slow components of LAr scintillation light. The designed background level of DEAP-3600 is less than 0.6 events in a 3000 kg·yr exposure. The experiment was filled in November 2016 and is currently taking dark matter search data.
The questionnaire "Fragebogen zur Erfassung des stimmlichen Selbstkonzepts (FESS)" was published in 2015 by Nusseck et al. It consists of 17 items measuring 3 scales on voice related self-concept. ...This paper examines the distribution of scale values in young adults by examination of medical students.
96 FESS questionnaires were filled in by medical students. An additional item was added, stating whether it felt easy to answer the questionnaire. The distribution of the scales as well as percentile ranks are given in the paper.
In all 3 scales there were no significant differences between females and males, therefore they were analysed as one group. The distributions of all 3 scales show no relevant ceiling nor floor effects. Probands with lower scores in 2 of the three scales found it less easy to answer the questions.
The results encourage the use of the questionnaire in patients. There was no indication of relevant floor or ceiling effects and there was enough variance in each scale. If used in patients further investigation is needed on the result that patients with lower scores tend to find it more difficult to fill in the questionnaire. The percentile ranks published herein are valid for medical students at this stage. Until bigger normative data on more diverse populations are conducted we will use these data as an orientation to judge other young adults' scores, too.
A first search for rare decays of gadolinium isotopes was performed with an ultra-low background high-purity germanium detector at Gran Sasso Underground Laboratory (Italy). A 198 g
Gd
2
O
3
powder ...sample was measured for 63.8 d with a total Gd exposure of 12.6 kg
×
d.
152
Gd is the most promising isotope for resonant enhanced neutrinoless double electron capture which could significantly increase the decay rate over other neutrinoless double beta decay processes. The half-life for this decay was constrained to
>
4.2
×
10
12
year (90% credibility). This limit is still orders of magnitude away from theoretical predictions but it is the first established limit on the transition paving the way for future experiments. In addition, other rare alpha and double beta decay modes were investigated in
152
Gd,
154
Gd, and
160
Gd with half-life limits in the range of
10
17
-
20
year.
A search for alpha and double beta decays of ytterbium isotopes was performed with an ultra low-background high purity germanium detector at Gran Sasso Underground Laboratory (Italy). A 194.7 g Yb
2
...(C
2
O
4
)
3
powder sample was measured for 11.3 days with a total Yb exposure of 1.25 kg
×
day. Half-life limits for
α
-decay modes of
168
Y
b
,
170
Y
b
,
171
Y
b
,
172
Y
b
,
173
Y
b
,
174
Y
b
and
176
Y
b
into the first excited states have been obtained between
6
×
10
14
years and
2
×
10
16
years. These are the first experimental constraints of these decay modes. Double electron capture of
168
Y
b
and double beta decay of
176
Y
b
into the first excited 2
+
and 0
+
states could be excluded with limits between
1
×
10
14
years to
8
×
10
16
years. This improves the experimental information on some of the decay modes compared to previous constraints.
First limits on double beta decays in 232Th Laubenstein, M.; Lehnert, B.; Nagorny, S. S.
The European physical journal. C, Particles and fields,
08/2020, Letnik:
80, Številka:
8
Journal Article
Recenzirano
Odprti dostop
As one of the primordial radioactive isotopes,
232
Th
mainly undergoes
α
-decay with a half-life of
1.402
·
10
10
years. However, it is also one of 35 double beta decay candidates in which the ...single
β
-decay is forbidden or strongly suppressed. 181 mg of thorium contained in a gas mantle were measured in a HPGe well-detector at the Gran Sasso Underground Laboratory with a total exposure of 3.25 g
×
d.
We obtain half-life limits on all double beta decay modes of
232
Th
to excited states of
232
U
on the order of
10
11
-
15
years. For the most likely transition into the 0
1
+
state we find a lower half-life limit of
6.7
·
10
14
years (90% C.I.). These are the first constraints on double beta decay excited state transition in
232
Th
.
As one of the primordial radioactive isotopes, Formula omitted mainly undergoes Formula omitted-decay with a half-life of Formula omitted years. However, it is also one of 35 double beta decay ...candidates in which the single Formula omitted-decay is forbidden or strongly suppressed. 181 mg of thorium contained in a gas mantle were measured in a HPGe well-detector at the Gran Sasso Underground Laboratory with a total exposure of 3.25 g Formula omittedd.
Increases in cell proliferation are widely viewed as being of importance in carcinogenesis. We report that exposure of normal human lung fibroblasts to a low dose of alpha particles like those ...emitted by radon/radon progeny stimulates their proliferation in vitro, and this response also occurs when unirradiated cells are treated with supernatants from alpha-irradiated cells. We attribute the promitogenic response to superoxide dismutase- and catalase-inhibitable a particle-induced increases in the concentrations of transforming growth factor beta1 (TGF-beta1) in cell supernatants. TGF-beta1 at concentrations commensurate with those in the supernatants capably induces increases in intracellular reactive oxygen species (ROS) in unirradiated cells. Furthermore, the addition of supernatants from alpha-irradiated cells to unirradiated cells decreases cellular levels of TP53 and CDKN1A and increases CDC2 and proliferating cell nuclear antigen in the latter. Like the increased intracellular ROS bystander effect, this "decreased TP53/CDKN1A response" can be mimicked in otherwise untreated cells by the addition of low concentrations of TGF-beta1. Our results indicate that alpha particle-associated increases in cell growth correlate with intracellular increases in ROS along with decreases in TP53 and CDKN1A, and that these cellular responses are mechanistically coupled. As well, the proliferating cell nuclear antigen and CDC2 increases that occur along with the decreased TP53/CDKN1A bystander effect also would expectedly favor enhanced cell growth. Such processes may account for cell hyperplastic responses in the conducting airways of the lower respiratory track that occur after inhalation exposure to radon/ radon progeny, as well as, perhaps, other ROS-associated environmental stresses.
180
m
Ta
is the longest-lived metastable state presently known. Its decay has not been observed yet. In this work, we report a new result on the decay of
180
m
Ta
obtained with a 2015.12-g tantalum ...sample measured for 527.7 d with an ultra-low background HPGe detector in the STELLA laboratory of the Laboratori Nazionali del Gran Sasso (LNGS), in Italy. Before the measurement, the sample has been stored deep-underground for ten years, resulting in subdominant background contributions from cosmogenically activated
182
Ta
. We observe no signal in the regions of interest and set half-life limits on the process for the two channels EC and
β
-
:
T
1
/
2
,
EC
>
1.6
×
10
18
year and
T
1
/
2
,
β
-
>
1.1
×
10
18
year (90% C. I.), respectively. We also set the limit on the
γ
de-excitation / IC channel:
T
1
/
2
,
IC
>
4.1
×
10
15
year (90% C. I.). These are, as of now, the most stringent bounds on the decay of
180
m
Ta
worldwide. Finally, we test the hypothetical scenarios of de-excitation of
180
m
Ta
by cosmological Dark Matter and constrain new parameter space for strongly-interacting dark-matter particle with mass up to
10
5
GeV.
The mechanism(s) by which high-linear energy transfer a particles, like those emitted by inhaled radon and radon daughters, cause lung cancer has not been elucidated. Conceivably, DNA damage that is ...induced by a particles may be mediated by the metabolic generation of reactive oxygen species (ROS), in addition to direct a particle-DNA interactions and hydroxyl radical-DNA interactions. Using normal human lung fibroblasts, we investigated the hypothesis that densely ionizing alpha particles may induce the intracellular generation of superoxide (O2.-) and hydrogen peroxide (H2O2). Ethidium bromide and 2',7'-dichlorofluorescein, fluorescent products of the membrane-permeable dyes hydroethidine and 2',7'-dichlorofluorescin diacetate, respectively, were used to monitor the intracellular production of O2.- and H2O2, respectively, by flow cytometry. Compared to sham-irradiated cells, fibroblasts that were exposed to alpha particles (0.4-19 cGy) had significant increases in intracellular O2.- production, along with concomitant increases in H2O2 production. Further analyses suggest that the plasma membrane-bound NADPH-oxidase is primarily responsible for this increased intracellular generation of ROS and that the ROS response does not require direct nuclear or cellular "hits" by the a particles. In this latter regard, we additionally report that unirradiated cells also show the ROS response when they are incubated with serum-containing culture medium that has been exposed to a particles or when they are incubated with supernatants from a-irradiated cells. Our overall results support the possibility that a particles, at least in part, may mediate their DNA-damaging effects indirectly via a ROS-related mechanism.
Dosimetry parameters such as deposition, clearance, retention, and translocation and dissolution of inhaled particles in and to different lung compartments may be important for the persistence of ...particles in the lung and may correlate with adverse pulmonary effects. We investigated such correlations using a model involving TiO2particles of two particle sizes (20 nm diameter, ultrafine; 250 nm diameter, fine) of the same crystalline structure (anatase). A 12-week inhalation experiment in rats resulted in a similar mass deposition of the two particle types in the lower respiratory tract. The ultrafine particles elicited a persistently high inflammatory reaction in the lungs of the animals compared to the larger-sized particles. In the postexposure period (up to 1 year) retention in the alveolar space per se was not different between fine and ultrafine TiO2. However, the following differences between the particle types were noted: a significantly different total pulmonary retention, both quantitatively (significantly prolonged retention of the ultrafine TiO2) and qualitatively (increased translocation to the pulmonary interstitium and persistence there of the ultrafine TiO2); greater epithelial effects (Type II cell proliferation; occlusion of pores of Kohn) and the beginning of interstitial fibrotic foci with ultrafine TiO2; significant sustained impairment of alveolar macrophage function after ultrafine TiO2exposure as measured by the clearance of test particles. A correlation between particle surface area and effects was observed. A comparison of the adverse reactions with dosimetric parameters of TiO2in different lung compartments in the postexposure period showed a correlation of the persistence of effects in both the alveolar and interstitial space with the persistence of particles in the respective compartment.
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