158 research outputs found
The ABC Effect in Double-Pionic Nuclear Fusion and a pn Resonance as its Possible Origin
The ABC effect -- a long-standing puzzle in double-pionic fusion -- has been
reexamined by the first exclusive and kinematically complete measurements of
solid statistics for the fusion reactions , He and He using the WASA detector, first at
CELSIUS and recently at COSY -- the latter with a statistics increased by
another two orders of magnitude. In all cases we observe a huge low-mass
enhancement in the -invariant mass accompanied by a pronounced
excitation. For the most basic fusion reaction, the reaction, we observe in addition a very pronounced resonance-like
energy dependence in the total cross section with a maximum 90 MeV below the
mass and a width of only 50 MeV, which is five times smaller
than expected from a conventional -channel excitation. This
reveals the ABC effect to be the consequence of a s-channel resonance with the
formfactor of this dibaryonic state being reflected in the low-mass enhancement
of the -invariant mass. From the fusion reactions to He and He
we learn that this resonance is robust enough to survive even in nuclei.Comment: conference proceedings PANIC 0
A calorimeter coupled with a magnetic spectrometer for the detection of primary cosmic antiprotons
A tracking calorimeter made of 3200 brass streamer tubes together with 3200 pick-up strips has been built to complement a magnetic spectrometer in order to detect cosmic antiprotons in space. The characteristics of such a calorimeter, the results of a preliminary test of a prototype as well as the properties of the whole apparatus are presented. The apparatus, designed to operate on a balloon at an altitude of about 40 km, can be considered as a second generation detector, capable in principle to solve the problem of the presence of low energy (≤1 Ge V/c) antiprotons in the cosmic rays which is still open because of the disagreement between the existent experimental data
SINEUP non-coding RNA activity depends on specific N6-methyladenosine nucleotides
SINEUPs are natural and synthetic antisense long non-coding RNAs (lncRNAs) selectively enhancing target mRNAs translation by increasing their association with polysomes. This activity requires two RNA domains: an embedded inverted SINEB2 element acting as effector domain, and an antisense region, the binding domain, conferring target selectivity. SINEUP technology presents several advantages to treat genetic (haploinsufficiencies) and complex diseases restoring the physiological activity of diseased genes and of compensatory pathways. To streamline these applications to the clinic, a better understanding of the mechanism of action is needed. Here we show that natural mouse SINEUP AS Uchl1 and synthetic human miniSINEUP-DJ-1 are N6-methyladenosine (m6A) modified by METTL3 enzyme. Then, we map m6A-modified sites along SINEUP sequence with Nanopore direct RNA sequencing and a reverse transcription assay. We report that m6A removal from SINEUP RNA causes the depletion of endogenous target mRNA from actively translating polysomes, without altering SINEUP enrichment in ribosomal subunit-associated fractions. These results prove that SINEUP activity requires an m6A-dependent step to enhance translation of target mRNAs, providing a new mechanism for m6A translation regulation and strengthening our knowledge of SINEUP-specific mode of action. Altogether these new findings pave the way to a more effective therapeutic application of this well-defined class of lncRNAs
Atmospheric neutrino flux supported by recent muon experiments
We present a new one-dimensional calculation of low and intermediate energy
atmospheric muon and neutrino fluxes, using up-to-date data on primary cosmic
rays and hadronic interactions. We study several sources of uncertainties
relevant to our calculations. A comparison with the muon fluxes and charge
ratios measured in several modern balloon-borne experiments suggests that the
atmospheric neutrino flux is essentially lower than one used for the standard
analyses of the sub-GeV and multi-GeV neutrino induced events in underground
detectors.Comment: 23 pages, 7 figures, 2 tables. Typos corrected, figure layout
improved, references added. Final version accepted for publication in PL
Cosmic-ray spectra of primary protons and high altitude muons deconvolved from observed atmospheric gamma rays
We have observed atmospheric gamma rays from 30GeV to 8TeV, using emulsion
chambers at balloon altitudes, accumulating the largest total exposure in this
energy range to date, SOT ~ 6.66m^2.sr.day. At very high altitudes, with
residual overburden only a few g/cm^2, atmospheric gamma rays are mainly
produced by a single interaction of primary cosmic rays with overlying
atmospheric nuclei. Thus, we can use these gamma rays to study the spectrum of
primary cosmic rays and their products in the atmosphere. From the observed
atmospheric gamma ray spectrum, we deconvolved the primary cosmic-ray proton
spectrum, assuming appropriate hadronic interaction models. Our deconvolved
proton spectrum covers the energy range from 200GeV to 50TeV, which fills a gap
in the currently available primary cosmic-ray proton spectra. We also estimated
the atmospheric muon spectrum above 30GeV at high altitude from our gamma-ray
spectrum, almost without reference to the primary cosmic rays, and compared the
estimated flux with direct muon observations below 10GeV.Comment: 13pages, 11 figures. Accepted for publication in PR
Balloon Measurements of Cosmic Ray Muon Spectra in the Atmosphere along with those of Primary Protons and Helium Nuclei over Mid-Latitude
We report here the measurements of the energy spectra of atmospheric muons
and of the cosmic ray primary proton and helium nuclei in a single experiment.
These were carried out using the MASS superconducting spectrometer in a balloon
flight experiment in 1991. The relevance of these results to the atmospheric
neutrino anomaly is emphasized. In particular, this approach allows
uncertainties caused by the level of solar modulation, the geomagnetic cut-off
of the primaries and possible experimental systematics to be decoupled in the
comparison of calculated fluxes of muons to measured muon fluxes. The muon
observations cover the momentum and depth ranges of 0.3-40 GeV/c and 5-886
g/cmsquared, respectively. The proton and helium primary measurements cover the
rigidity range from 3 to 100 GV, in which both the solar modulation and the
geomagnetic cut-off affect the energy spectra at low energies.Comment: 31 pages, including 17 figures, simplified apparatus figure, to
appear in Phys. Rev.
Measurement of the flux of atmospheric muons with the CAPRICE94 apparatus
A new measurement of the momentum spectra of both positive and negative muons
as function of atmospheric depth was made by the balloon-borne experiment
CAPRICE94. The data were collected during ground runs in Lynn Lake on the
19-20th of July 1994 and during the balloon flight on the 8-9th of August 1994.
We present results that cover the momentum intervals 0.3-40 GeV/c for negative
muons and 0.3-2 GeV/c for positive muons, for atmospheric depths from 3.3 to
1000 g/cm**2, respectively. Good agreement is found with previous measurements
for high momenta, while at momenta below 1 GeV/c we find latitude dependent
geomagnetic effects. These measurements are important cross-checks for the
simulations carried out to calculate the atmospheric neutrino fluxes and to
understand the observed atmospheric neutrino anomaly.Comment: 28 pages, 13 Postscript figures, uses revtex.sty, to appear in Phys.
Rev.
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