21 research outputs found
Development of High Granulated Straw Chambers of Large Sizes
We have developed the baseline design for the straw drift tube tracking
detectors for high rate environment application. The low-mass inner straw
elements and the technology of the multianode straws assembly was devised and
checked. The prototype chamber was constructed and studied the granularity of
similar chambers can be reduced to one cm2.
Submitted to Physics of Elementary Particles and Atomic Nuclei, LettersComment: 6 pages, 10 figure
On detection of narrow angle e+e- pairs from dark photon decays
A class of models of dark sectors consider new very weak interaction between
the ordinary and dark matter transmitted by U'(1) gauge bosons A' (dark
photons) mixing with our photons. If such A's exist, they could be searched for
in a light-shining-through-a-wall experiment with a high energy electron beam
from the CERN SPS. The proposed search scheme suggests detection of the e+e-
pairs produced in the A' -> e+e- decay with a very small opening angle.
Coordinate chambers based on the thin-wall drift tubes with a minimal material
budget and a two-hit resolution for e+ and e- tracks separated by more than 0.5
mm are considered as an option for detecting such pairs
Search for invisible decays of sub-GeV dark photons in missing-energy events at the CERN SPS
We report on a direct search for sub-GeV dark photons (A') which might be
produced in the reaction e^- Z \to e^- Z A' via kinetic mixing with photons by
100 GeV electrons incident on an active target in the NA64 experiment at the
CERN SPS. The A's would decay invisibly into dark matter particles resulting in
events with large missing energy. No evidence for such decays was found with
2.75\cdot 10^{9} electrons on target. We set new limits on the \gamma-A' mixing
strength and exclude the invisible A' with a mass < 100 MeV as an explanation
of the muon g_\mu-2 anomaly.Comment: 6 pages, 3 figures; Typos corrected, references adde
Statistique mensuelle de la viande. 1968 N° 4 APRIL-AVRIL = Monthly statistiques of meat. 1968 No. 4 April
In high energy experiments such as active beam dump searches for rare decays and missing energy events, the beam purity is a crucial parameter. In this paper we present a technique to reject heavy charged particle contamination in the 100 GeV electron beam of the H4 beam line at CERN SPS. The method is based on the detection with BGO scintillators of the synchrotron radiation emitted by the electrons passing through a bending dipole magnet. A 100 GeV pi- beam is used to test the method in the NA64 experiment resulting in a suppression factor of 10−5 while the efficiency for electron detection is 95%. The spectra and the rejection factors are in very good agreement with the Monte Carlo simulation. The reported suppression factors are significantly better than previously achieved.ISSN:0168-9002ISSN:1872-957