Helicity-dependent total photoabsorption cross sections on the deuteron have been measured for the first time at ELSA (Bonn) in the photon energy range from 815 to 1825 MeV. Circularly polarized ...tagged photons impinging on a longitudinally polarized LiD target have been used together with a highly efficient 4pi detector system. The data around 1 GeV are not compatible with predictions from existing multipole analyses. From the measured energy range an experimental contribution to the GDH integral on the neutron of 33.9 +/- 5.5(stat) +/- 4.5(syst) microb is extracted.
We report on studies of the viability and sensitivity of the Askaryan Radio Array (ARA), a new initiative to develop a Teraton-scale ultra-high energy neutrino detector in deep, radio-transparent ice ...near Amundsen-Scott station at the South Pole. An initial prototype ARA detector system was installed in January 2011, and has been operating continuously since then. We describe measurements of the background radio noise levels, the radio clarity of the ice, and the estimated sensitivity of the planned ARA array given these results, based on the first five months of operation. Anthropogenic radio interference in the vicinity of the South Pole currently leads to a few-percent loss of data, but no overall effect on the background noise levels, which are dominated by the thermal noise floor of the cold polar ice, and galactic noise at lower frequencies. We have also successfully detected signals originating from a 2.5km deep impulse generator at a distance of over 3 km from our prototype detector, confirming prior estimates of kilometer-scale attenuation lengths for cold polar ice. These are also the first such measurements for propagation over such large slant distances in ice. Based on these data, ARA-37, the ∼200km2 array now in its initial construction phase, will achieve the highest sensitivity of any planned or existing neutrino detector in the 1016–1019eV energy range.
In this work we present a keV-scale sterile-neutrino search with a low-tritium-activity data set of the KATRIN experiment, acquired in a commissioning run in 2018. KATRIN performs a spectroscopic ...measurement of the tritium β-decay spectrum with the main goal of directly determining the effective electron anti-neutrino mass. During this commissioning phase a lower tritium activity facilitated the measurement of a wider part of the tritium spectrum and thus the search for sterile neutrinos with a mass of up to 1.6 keV. We do not find a signal and set an exclusion limit on the sterile-to-active mixing amplitude of $\text {sin}^{2}\: \theta<5\times 10^{-4}\: (95\%\: $C.L) at a mass of 0.3 keV. This result improves current laboratory-based bounds in the sterile-neutrino mass range between 0.1 and 1.0 keV.
The GDH-Møller-Polarimeter at ELSA Speckner, T.; Anton, G.; von Drachenfels, W. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
3/2004, Volume:
519, Issue:
3
Journal Article
Muon track reconstruction and data selection techniques in AMANDA Ahrens, J.; Bai, X.; Bay, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2004, Volume:
524, Issue:
1
Journal Article
Peer reviewed
Open access
The Antarctic Muon And Neutrino Detector
Array (AMANDA) is a high-energy neutrino telescope operating at the geographic South Pole. It is a lattice of photo-multiplier tubes buried deep in the polar ...ice between 1500 and
2000
m
. The primary goal of this detector is to discover astrophysical sources of high-energy neutrinos. A high-energy muon neutrino coming through the earth from the Northern Hemisphere can be identified by the secondary muon moving upward through the detector.
The muon tracks are reconstructed with a maximum likelihood method. It models the arrival times and amplitudes of Cherenkov photons registered by the photo-multipliers. This paper describes the different methods of reconstruction, which have been successfully implemented within
AMANDA. Strategies for optimizing the reconstruction performance and rejecting background are presented. For a typical analysis procedure the direction of tracks are reconstructed with about 2° accuracy.
The GDH-Detector Helbing, K; Anton, G; Fausten, M ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2002, Volume:
484, Issue:
1
Journal Article
Peer reviewed
For the GDH-Experiment at E
LSA, the helicity dependent total photoabsorption cross-section is to be determined. These measurements will be performed with the newly developed GDH-Detector which is ...presented here. The concept of the GDH-Detector is to detect at least one reaction product from all possible hadronic processes with almost complete acceptance concerning solid angle and efficiency. This is realized by an arrangement of scintillators and lead. The overall acceptance for hadronic processes is better than 99%. The electromagnetic background is suppressed by about five orders of magnitude by means of a threshold Cherenkov detector. In dedicated tests, it has been demonstrated that all individual components of the GDH-Detector fulfill the design goals. Measurements of unpolarized total photoabsorption cross-sections were performed to ensure that the complete GDH-Detector is operational.
A photon tagging system for the GDH-Experiment at ELSA Naumann, J.; Anton, G.; Bock, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2003, Volume:
498, Issue:
1
Journal Article
Peer reviewed
This paper describes the set-up and calibration of the tagging system of the GDH-Experiment at the accelerator facility E
lsa in Bonn. The system consists of a C-type dipole magnet and a hodoscope of ...65 scintillation counters which are operated pairwise in coincidence to form 64 tagging channels. Photons can be tagged in a range of 68–97% of the primary electron energy
E
0. The energy resolution ranges from 0.2% to 0.6% of
E
0. The time resolution is better than
165
ps
. The system was operated at rates up to
5×10
6
photons/s
in the full tagged energy range. The energy dependence of the photon definition probability was determined using several different methods and was found to agree well with calculations.
An active collimator system for a high-energy photon beam Zeitler, G; Anton, G; Bock, A ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2001, Volume:
459, Issue:
1
Journal Article
Peer reviewed
Active collimators are designed to both collimate the tagged photon beam and suppress the background of secondary photons. These secondary photons are generated by interaction processes in the ...collimator medium. They may reach the hadron target with a lower energy compared to the energy determined by the tagging system. Accordingly, those events are tagged with a wrong energy and have to be rejected. By means of a Monte Carlo simulation we investigated the effect and the performance of an active collimator system and developed an optimal design of the collimators to prepare a clean high-energy photon beam. The resulting set-up ensures a precise determination of the tagging efficiency and of the photon flux. The active collimators are a necessary tool to correctly determine photoproduction cross-sections. Results of test measurements at ELSA in Bonn, and MAMI B in Mainz are discussed. Special interest is given to the use of the active collimators in the experiment to test the GDH sum rule at ELSA up to
3.2
GeV
.
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