1,276 research outputs found
Test facility for experimental investigations of the He-II based ET-LF payload cooling concept
The Performance of the AMS-02 Trd
The Alpha Magnetic Spectrometer (AMS-02) is an experiment which will be mounted on the International Space Station (ISS) in 2007 to measure primary cosmic ray spectra in space and to perrform an indirect search for dark matter in the universe. To this aim, AMS includes a Transition Radiation Detector (TRD) to be able to distinguish an e+ or psignal, reducing the p+/ebackground by a rejection factor 10.' in the energy range 10-300 GeV. The TRD will be used in conjuction with an electromagnetic calorimeter to provide overall p+ rejection of at 90% e+ efficiency. A TRD prototype has been calibrated and its performance measured in test beams with p', e', F-, 71from 3 to 250 GeV/c and compared with Montecarlo predictions. It achieved a rejection factor ranging from 2000 to 140 for protons with energy varying from 15 to 250 GeV. The TRD Modules and structures have undergone an extensive program of space qualification. Selected Modules have undergone a long term test in a vacuum chamber. TRD flight version is under construction, and so far within specifications and schedule
Test facility for experimental investigations of the He-II based ET-LF payload cooling concept
The Einstein Telescope (ET) is a third generation gravitational wave detector, combining a low-frequency (LF) and a high-frequency (HF) laser interferometer. Cryogenic operation of ET-LF in the temperature range of 10-20 K is essential to suppress the suspension thermal noise (STN), which dominates the detection sensitivity at frequencies below 10 Hz. The minimization of the STN requires suspension materials with high thermal conductivity and low mechanical dissipation at cryogenic temperatures. Motivated by the exceptional heat conductivity of static He-II and a presumably low dissipation, a new marionette suspension design with a He-II filled titanium tube has been proposed and, theoretically, shown to meet the ET-D sensitivity requirements. The concept includes open fundamental questions that can only be addressed by measurements of the mechanical Q-factor, providing crucial insights in the dissipative behaviour of such a system. Hence, an experimental setup for cryogenic Q-factor measurements is being planned. The scope of experiments and a first conceptual design are being presented here. Beside the Q-factor measurements, a main focus of this facility is given to R&D on the integration of the He-II system and the mechanical interface to the payload in view of noise isolation
Conceptual cryostat design for cryogenic suspension studies for the Einstein Telescope
The Einstein Telescope (ET) is a third generation gravitational wave detector, combining a low-frequency (LF) and a high-frequency (HF) laser interferometer. Cryogenic operation of ET-LF in the temperature range of 10K to 20K is essential to suppress the suspension thermal noise, which dominates the detection sensitivity at frequencies below 10 Hz. This requires suspension materials with high thermal conductivity and low mechanical dissipation at cryogenic temperatures. Two possible suspension concepts are currently considered, using either monocrystalline suspension fibers made of silicon or sapphire, or titanium suspension tubes filled with static He-II. The dissipative behavior of these suspensions is characterized by the mechanical Q-factor. It can be measured by the ring-down method, exciting the suspensions to resonance vibrations on the nanometer scale and analyzing the decay time. For this purpose, a new cryogenic test facility is being planned, allowing the investigation of cryogenic payload suspensions for third-generation gravitational wave detectors. The test cryostat is equipped with a cryocooler and enables real-size studies with various suspension materials and geometries. The future integration of He-II is foreseen to enable He-II filled suspension studies. We describe the scope of experiments and the conceptual design of the test cryostat
Cryogenic payloads for the Einstein Telescope -- Baseline design with heat extraction, suspension thermal noise modelling and sensitivity analyses
The Einstein Telescope (ET) is a third generation gravitational wave detector
that includes a room-temperature high-frequency (ET-HF) and a cryogenic
low-frequency laser interferometer (ET-LF). The cryogenic ET-LF is crucial for
exploiting the full scientific potential of ET. We present a new baseline
design for the cryogenic payload that is thermally and mechanically consistent
and compatible with the design sensitivity curve of ET. The design includes two
options for the heat extraction from the marionette, based on a monocrystalline
high-conductivity marionette suspension fiber and a thin-wall titanium tube
filled with static He-II, respectively. Following a detailed description of the
design options and the suspension thermal noise (STN) modelling, we present the
sensitivity curves of the two baseline designs, discuss the influence of
various design parameters on the sensitivity of ET-LF and conclude with an
outlook to future R&D activities.Comment: 20 pages, Article to be published/submitted in Physical Review D -
Journa
Measurement of 1323 and 1487 keV resonances in 15N({\alpha}, {\gamma})19F with the recoil separator ERNA
The origin of fluorine is a widely debated issue. Nevertheless, the
^{15}N({\alpha},{\gamma})^{19}F reaction is a common feature among the various
production channels so far proposed. Its reaction rate at relevant temperatures
is determined by a number of narrow resonances together with the DC component
and the tails of the two broad resonances at E_{c.m.} = 1323 and 1487 keV.
Measurement through the direct detection of the 19F recoil ions with the
European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The
reaction was initiated by a 15N beam impinging onto a 4He windowless gas
target. The observed yield of the resonances at Ec.m. = 1323 and 1487 keV is
used to determine their widths in the {\alpha} and {\gamma} channels. We show
that a direct measurement of the cross section of the
^{15}N({\alpha},{\gamma})^{19}F reaction can be successfully obtained with the
Recoil Separator ERNA, and the widths {\Gamma}_{\gamma} and {\Gamma}_{\alpha}
of the two broad resonances have been determined. While a fair agreement is
found with earlier determination of the widths of the 1487 keV resonance, a
significant difference is found for the 1323 keV resonance {\Gamma}_{\alpha} .
The revision of the widths of the two more relevant broad resonances in the
15N({\alpha},{\gamma})19F reaction presented in this work is the first step
toward a more firm determination of the reaction rate. At present, the residual
uncertainty at the temperatures of the ^{19}F stellar nucleosynthesis is
dominated by the uncertainties affecting the Direct Capture component and the
364 keV narrow resonance, both so far investigated only through indirect
experiments.Comment: 8 pages, 11 figures. Accepted for publication in PR
Displacement power spectrum measurement of a macroscopic optomechanical system at thermal equilibrium
The mirror relative motion of a suspended Fabry-Perot cavity is studied in
the frequency range 3-10 Hz. The experimental measurements presented in this
paper, have been performed at the Low Frequency Facility, a high finesse
optical cavity 1 cm long suspended to a mechanical seismic isolation system
identical to that one used in the VIRGO experiment. The measured relative
displacement power spectrum is compatible with a system at thermal equilibrium
within its environmental. In the frequency region above 3 Hz, where seismic
noise contamination is negligible, the measurement distribution is stationary
and Gaussian, as expected for a system at thermal equilibrium. Through a simple
mechanical model it is shown that: applying the fluctuation dissipation theorem
the measured power spectrum is reproduced below 90 Hz and noise induced by
external sources are below the measurement.Comment: 11 pages, 9 figures, 2 tables, to be submitte
Magnetic coupling to the Advanced Virgo payloads and its impact on the low frequency sensitivity
We study the electromagnetic coupling of the Advanced Virgo (AdV) Input
Mirror Payload (IMP) in response to a slowly time-varying magnetic field. As
the problem is not amenable to analytical solution, we employ and validate a
finite element (FE) analysis approach. The FE model is built to represent as
faithfully as possible the real object and it has been validated by comparison
with experimental measurements. The intent is to estimate the induced currents
and the magnetic field in the neighbourhood of the payload. The procedure found
21 equivalent electrical configurations that are compatible with the
measurements. These have been used to compute the magnetic noise contribution
to the total AdV strain noise. At the current stage of development AdV seems to
be unaffected by magnetic noise, but we foresee a non-negligible coupling once
AdV reaches the design sensitivity.Comment: 8 pages, 8 figures, 2 table
Underground Measurements of Nuclear Reaction Cross-Sections Relevant to AGB Stars
none14noneAnanna, Chemseddine; Barile, Francesco; Boeltzig, Axel; Bruno, Carlo Giulio; Cavanna, Francesca; Ciani, Giovanni Francesco; Compagnucci, Alessandro; Csedreki, Laszlo; Depalo, Rosanna; Ferraro, Federico; Masha, Eliana; Piatti, Denise; Rapagnani, David; Skowronski, JakubAnanna, Chemseddine; Barile, Francesco; Boeltzig, Axel; Bruno, Carlo Giulio; Cavanna, Francesca; Ciani, Giovanni Francesco; Compagnucci, Alessandro; Csedreki, Laszlo; Depalo, Rosanna; Ferraro, Federico; Masha, Eliana; Piatti, Denise; Rapagnani, David; Skowronski, Jaku
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