ABSTRACT
PAON4 is an L-band (1250–1500 MHz) small interferometer operating in transit mode deployed at the Nançay observatory in France, designed as a prototype instrument for intensity mapping. It ...features four 5 m diameter dishes in a compact triangular configuration, with a total geometric collecting area of ${\sim} 75\, \mathrm{m^2}$, and is equipped with dual polarization receivers. A total of 36 visibilities are computed from the eight independent RF signals by the software correlator over the full 250 MHz RF band. The array operates in transit mode, with the dishes pointed toward a fixed declination, while the sky drifts across the instrument. Sky maps for each frequency channel are then reconstructed by combining the time-dependent visibilities from the different baselines observed at different declinations. This paper presents an overview of the PAON4 instrument design and goals, as a prototype for dish arrays to map the large-scale structure in radio, using intensity mapping of the atomic hydrogen 21 cm line. We operated PAON4 over several years and use data from observations at different periods to assess the array performance. We present a preliminary analysis of a large fraction of these data and discuss crucial issues for this type of instrument, such as the calibration strategy, instrument response stability and noise behaviour.
The Olimpo balloon project will use a 120 bolometer camera to observe the sky at four frequencies (143, 217, 385 and 600
GHz) with a resolution of 3 to 2 arc-minute. This paper presents the ...sub-millimeter calibration “lamp” developed for ground testing and in-flight secondary calibration of bolometric detectors. By design, main features of the device are reproducibility and stability of light flux and millisecond rise time. The radiative device will be placed inside the bolometer camera and will illuminate the bolometer array through a hole in the last 2
K mirror. Operation, readout, and monitoring of the device is ensured by warm electronics. Light output flux and duration is programmable, triggered and monitored from a simple computer
RS
232
interface. It was tested to be reliable in ballooning temperature conditions from
-
80
to
50
∘
C
. Design and test's results are explained.
Micromegas as a large microstrip detector for the COMPASS experiment Thers, D; Abbon, Ph; Ball, J ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2001, Volume:
469, Issue:
2
Journal Article
Peer reviewed
Open access
Recent results on the gaseous microstrip detector Micromegas which will be used to track particles in the COMPASS experiment at CERN are presented. Developments concerning its mechanical and ...electrical design, associated readout electronics and gas mixture were carried out. Particular attention was paid to the discharge phenomenon which affects this type of microstrip detector. The adequacy of the options finally retained, especially the SFE16 readout and the use of a Ne–C
2H
6–CF
4 gas mixture, was demonstrated in a set of beam tests performed on a
26×36
cm
2
prototype. Operating at a gain of ∼6400, full efficiency is reached along with a spatial resolution of
∼50
μm
and a timing accuracy of
8.5
ns
. Discharges are kept at a low rate, less than one per SPS spill in a COMPASS-like environment. Via a decoupling of the strips through individual capacitors their impact is greatly reduced. They generate a dead time on the full detector of
∼
3
ms
, affecting marginally the detection efficiency given their rate. The probability of discharge, at a given value of efficiency, is found to decrease with the mean value of the gas mixture atomic number. In view of these results, the commissioning of Micromegas for COMPASS is foreseen in the near future.
PAON4 is an L-band (1250-1500 MHz) small interferometer operating in transit mode deployed at the Nançay observatory in France, designed as a prototype instrument for Intensity Mapping. It features ...four 5~meter diameter dishes in a compact triangular configuration, with a total geometric collecting area of \(\sim75 \mathrm{m^2}\), and equipped with dual polarization receivers. A total of 36 visibilities are computed from the 8 independent RF signals by the software correlator over the full 250~MHz RF band. The array operates in transit mode, with the dishes pointed toward a fixed declination, while the sky drifts across the instrument. Sky maps for each frequency channel are then reconstructed by combining the time-dependent visibilities from the different baselines observed at different declinations. This paper presents an overview of the PAON4 instrument design and goals, as a prototype for dish arrays to map the Large Scale Structure in radio, using intensity mapping of the atomic hydrogen \(21~\mathrm{cm}\) line. We operated PAON4 over several years and use data from observations in different periods to assess the array performance. We present preliminary analysis of a large fraction of this data and discuss crucial issues for this type of instrument, such as the calibration strategy, instrument response stability, and noise behaviour.
Micromegas, a microstrip detector for Compass Abbon, Ph; Ball, J.; Bedfer, Y. ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
04/2001, Volume:
461, Issue:
1
Journal Article, Conference Proceeding
Peer reviewed
Recent results obtained with a gaseous microstrip detector Micromegas developed for the tracking in the high-rate environment of the COMPASS experiment at CERN are presented. A
26×36
cm
2
prototype ...equipped with the low-noise preamplifier SFE16 was tested in a high-energy hadron beam at CERN. With a gas mixture based on neon, the full efficiency of the Micromegas prototype is obtained at a gain of 6400; the spatial resolution is 50
μm and the time jitter 8.5
ns. We have studied the problem of discharges that affect this kind of microstrip detector, and found that, at fixed gain, the probability of discharge is higher for heavier gas mixtures in the detector. In the conditions of the COMPASS experiment, discharges are kept at a low rate.
Between 2002 and 2006, the COMPASS high-rate experiment at CERN has been successful using the Micromegas technique to reach high performances in particle detection. The twelve 40 cm times 40 cm ...Micromegas planes, the largest gaseous micro-pattern detectors ever used to date in a high energy experiment, provide an excellent tracking device in the hottest part of the spectrometer, even with the use of hadron beams. The detectors see a total flux of 30 MHz, with rates reaching 5 kHz/mm 2 in the region close to the beam. So far, they have accumulated more than 1 mC/mm 2 in their central region without experiencing any damage.
We propose to use MICROMEGAS, a new gaseous detector, in the tracking system of the COMPASS experiment. COMPASS will make use of the high energy (200 GeV) and high intensity (10
8s
−1) muon beam at ...CERN. MICROMEGAS chambers are good candidates for the tracking of leptons and hadrons in areas of0.2 m
2, with a high resolution (< 100 μm) and a low radiation length. Prototypes of MICROMEGAS were manufactured and tested at Saclay with a source of low energy electrons (
90Sr). The flux capabilities and the detection efficiency were studied using various gas mixtures.
We report here the characteristics of elementary devices and circuits when they are exposed at low temperature (≈ 90 K) to ionizing radiation. These devices and circuits are implemented in a ...radiation-hardened SOI monolithic technology. We have made irradiations both at high dose rates (≈ 100 krads/h) and low dose rate (≈ 0.02 krad/h), the low dose rate is of the order of magnitude of the value which should be encountered in high-energy physics calorimeters during future experiments. A reduction of the dose rate, at identical total dose received, has a favourable effect on the threshold voltage shift of MOSFETs and, consequently, on the behaviour of circuits designed with these devices. For example, a preamplifer remained functional with no significant change in its characteristics (noise and rise time) after ≈ 100 krads irradiation during a longer than 6 months exposure at 90 K (liquid-argon temperature). This is of key importance for the future development of silicon microelectronics for Liquid-Argon Calorimetry.
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