The antineutron–proton total cross section has been measured in the low momentum range 50–400 MeV/
c (below 100 MeV/
c for the first time). The measurement was performed at LEAR (CERN) by the OBELIX ...experiment, thanks to its unique antineutron beam facility. A thick target transmission technique has been used. The measured total cross section shows an anomalous behaviour below 100 MeV/
c. A dominance of the isospin
I=0 channel over the
I=1 one at low energy is clearly deduced.
Evidence for πK-atoms with DIRAC Adeva, B.; Afanasyev, L.; Allkofer, Y. ...
Physics letters. B,
04/2009, Letnik:
674, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We present evidence for the first observation of electromagnetically bound π±K∓-pairs (πK-atoms) with the DIRAC experiment at the CERN-PS. The πK-atoms are produced by the 24 GeV/c proton beam in a ...thin Pt-target and the π± and K∓-mesons from the atom dissociation are analyzed in a two-arm magnetic spectrometer. The observed enhancement at low relative momentum corresponds to the production of 173±54πK-atoms. The mean life of πK-atoms is related to the s-wave πK-scattering lengths, the measurement of which is the goal of the experiment. From these first data we derive a lower limit for the mean life of 0.8 fs at 90% confidence level.
DarkSide is direct-detection dark-matter experimental project based on radiopure argon. The main goal of the DarkSide program is the detection of rare nuclear elastic collisions with hypothetical ...dark-matter particles. The present detector, DarkSide-50, placed at Laboratori Nazionali del Gran Sasso (LNGS), is a dualphase time projection chamber (TPC) filled with ultra-pure liquid argon, extracted from underground sources. Surrounding the TPC to suppress the background there are neutron and muon active vetoes. One of argon key features is the capability to distinguish between electron and nuclear recoils, exploiting the different shapes of the signals. DarkSide-50 new results, obtained using a live-days exposure of 532.4 days, are presented. This analysis sets a 90% C.L. upper limit on the dark matter-nucleon spin-independent cross-section of 1.1 × 10-44 cm2 for a WIMP mass of 100 GeV/c2. The next phase of the project, DarkSide-20k, will be a new detector with a fiducial mass of ~ 20 tons, equipped with cryogenic silicon photomultipliers (SiPM).
Antiprotons stopping in xenon Lodi Rizzini, E.; Bianconi, A.; Bonomi, G. ...
Physics letters. B,
08/2001, Letnik:
513, Številka:
3
Journal Article
Recenzirano
Experimental data on p̄ slowing down at very low energy in a low density (0.2 mbar pressure) Xe target evidence a very low capture cross section with respect to He, H
2 and D
2 in agreement with ...specific phenomenological previsions by Briggs et al. Hyperfine Interact. 119 (1999) 235; J. Phys. B 32 (1999) 197.
The DIRAC experiment at CERN has achieved a sizeable production of
π
+
π
−
atoms and has significantly improved the precision on its lifetime determination. From a sample of 21 227 atomic pairs, a 4% ...measurement of the S-wave
ππ scattering length difference
|
a
0
−
a
2
|
=
(
0.2533
−
0.0078
+
0.0080
|
stat
|
syst
−
0.0073
+
0.0078
)
M
π
+
−
1
has been attained, providing an important test of Chiral Perturbation Theory.
The DIRAC experiment at CERN has achieved a sizeable production of Ie super(+Ie) super(-) atoms and has significantly improved the precision on its lifetime determination. From a sample of 21 227 ...atomic pairs, a 4% measurement of the S-wave IeIe scattering length difference inline image has been attained, providing an important test of Chiral Perturbation Theory.
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