Testa Grigia Research Articles

Long term measurements of neutron dose rates at Testa Grigia high altitude research station (3480 m. a.s.l.)

At the Testa Grigia high altitude research Station (3480 m. a.s.l, Italy, 45°57′ N, 7°42’ E) several dosimetric campaigns for the measurement of the dose due to secondary neutrons produced in the atmosphere and in the surrounding environment by primary cosmic rays have been carried out from 2014 until 2021. Because of the high altitude of the site, the neutron flux at Testa Grigia is 10–15 times higher than at the sea level. Various instruments has been used to evaluate the dependence of the ambient dose equivalent rate from different factors as atmospheric parameters, environmental conditions and solar activity. Moreover, since October 2014 a modular neutron monitor designed, realized and tested by the SVIRCO Observatory Group INAF-IAPS in Rome, is permanently operating in the laboratory, providing a continuous monitoring of primary cosmic ray variability and making the laboratory an ideal place for dosimetric studies, instrument calibration and “in field” tests. In this paper the results of several neutron measurements carried out in the last years in periods of different solar activity and environmental conditions are reported, with a discussion on the origin of the observed variations of the ambient dose equivalent rate.

Physiological Responses in Humans Acutely Exposed to High Altitude (3480 m): Minute Ventilation and Oxygenation Are Predictive for the Development of Acute Mountain Sickness.

The importance of arterial oxygen saturation for the prediction of acute mountain sickness (AMS) is still a matter of debate. Reasons for discrepancies may result from varying laboratory or field conditions and their interactions. Thus, we analyzed data from our prior high-altitude studies, including participants of a broad range of age of both sexes (20 males and 20 females, aged between 20 and 67 years) under strictly standardized conditions of pre-exposure and acute exposure to real high altitude (3480 m). A set of resting cardiovascular, respiratory, hematological, and metabolic variables were recorded at high altitude (Testa Grigia, Plateau Rosa, 3480 m; Swiss-Italian boarder) after performing pretests at low altitude (Innsbruck, 600 m, Austria). Our analyses indicate that (1) smaller changes in resting minute ventilation (VE) and a larger decrease of peripheral oxygen saturation (SpO2) during the first 3 hours of acute exposure to high altitude were independent predictors for subsequent development of AMS (90% correct prediction), (2) there are no differences of responses between sexes, and (3) there is no association of responses with age. Considering the independent effects of both responses (VE and SpO2) may be of clinical/practical relevance. Moreover, the presented data derived from a broad age range of both sexes might be of interest for comparative purposes.

Remote sensing of cirrus cloud microphysical properties using spectral measurements over the full range of their thermal emission

AbstractThe thermal emission of cirrus clouds, spectrally resolved in the 100–1400 cm−1 range (100–7.1 μm), has been modeled and compared with measurements performed during two field campaigns from the ground‐based site of Testa Grigia on the Italian Alps at 3480 m of altitude. The analysis of cirrus microphysics, through spectral fitting, shows the importance of using also the far infrared portion of the emitted spectrum at wave numbers below the 667 cm−1 carbon dioxide absorption band, where only a few measurements exist because of the high opacity of the atmosphere caused by the strong water vapor absorption. The resulted distribution of the fitted cloud parameters is in good agreement with the typical statistical distribution of the midlatitude cirrus cloud parameters.

RETRACTED ARTICLE: Piezonuclear neutron emissions from earthquakes and volcanic eruptions

Recent neutron emission detections have led to consider also the Earth’s crust, in addition to cosmic rays, as a relevant source of neutron flux variations. Neutron emissions measured in seismic areas of the Pamir region (4200 m a.s.l.) exceeded the usual neutron background level up to three orders of magnitude in correspondence to seismic activity and rather appreciable earthquakes of a magnitude of approximately the 4th degree in the Richter scale. The authors present an additional analysis with respect to those carried out by other research groups. Their studies start from recent data acquired at the “Testa Grigia” Laboratory of Plateau Rosa, Cervinia, during an experimental campaign on the evaluation of neutron radiation from cosmic rays. Even more recent data refer to dedicated experimental trials carried out in Northern Italy, at the seismic district of “Val Trebbia”, Bettola, Piacenza. Moreover, the authors present the results they are obtaining at a gypsum mine located in Murisengo (Alessandria), Italy. The observations reveal a strong correlation between AE/EME/NE events and the major earthquakes in the surrounding area. The assessment of the neutron radiation at an environmental level could help to make a clear distinction between the component from the Cosmic Rays and the component from the Earth’s crust.

Analysis of cirrus cloud spectral signatures in the far infrared

This paper analyses high spectral resolution downwelling radiance measurements in the far infrared in the presence of cirrus clouds taken by the REFIR-PAD interferometer, deployed at 3500m above the sea level at the Testa Grigia station (Italy), during the Earth COoling by WAter vapouR emission (ECOWAR) campaign. Atmospheric state and cloud geometry are characterised by the co-located millimeter-wave spectrometer GBMS and by radiosonde profile data, an interferometer (I-BEST) and a Raman lidar system deployed at a nearby location (Cervinia). Cloud optical depth and effective diameter are retrieved from REFIR-PAD data using a limited number of channels in the 820–960cm−1 interval. The retrieved cloud parameters are the input data for simulations covering the 250–1100cm−1 band in order to test our ability to reproduce the REFIR-PAD spectra in the presence of ice clouds. Inverse and forward simulations are based on the same radiative transfer code. A priori information concerning cloud ice vertical distribution is used to better constrain the simulation scheme and an analysis of the degree of approximation of the phase function within the radiative transfer codes is performed to define the accuracy of computations. Simulation-data residuals over the REFIR-PAD spectral interval show an excellent agreement in the window region, but values are larger than total measurement uncertainties in the far infrared. Possible causes are investigated. It is shown that the uncertainties related to the water vapour and temperature profiles are of the same order as the sensitivity to the a priori assumption on particle habits for an up-looking configuration. In case of a down-looking configuration, errors due to possible incorrect description of the water vapour profile would be drastically reduced.

An improved upper limit to the CMB circular polarization at large angular scales

Circular polarization of the Cosmic Microwave Background (CMB) offers thepossibility of detecting rotations of the universe and magneticfields in the primeval universe or in distant clusters of galaxies. We used the MilanoPolarimeter (MIPOL) installed at the Testa Grigia Observatory, on the italian Alps,to improve the existing upper limits to the CMBcircular polarization at large angular scales. We obtain 95% confidence level upper limits to the degree of the CMB circular polarization rangingbetween 5.0⋅10−4 and 0.7⋅10−4at angular scales between 8° and 24°, improvingby one order of magnitude preexisting upper limits at large angular scales.Our results are still far from thenK region where today expectations place the amplitude of the V Stokesparameter used to characterize circular polarization of the CMB but improvethe preexisting limit at similar angular scales.Our observations offered also the opportunity of characterizingthe atmospheric emission at 33 GHz at the Testa Grigia Observatory.

A template of atmospheric O2 circularly polarized emission for cosmic microwave background experiments

We compute the circularly polarized signal from atmospheric molecular oxygen. Polarization of O2 rotational lines is caused by Zeeman effect in the Earth magnetic field. We evaluate the circularly polarized emission for various sites suitable for CMB measurements: South Pole and Dome C (Antarctica), Atacama (Chile) and Testa Grigia (Italy). An analysis of the polarized signal is presented and discussed in the framework of future CMB polarization experiments. We find a typical circularly polarized signal (V Stokes parameter) of ~ 50 - 300 {\mu}K at 90 GHz looking at the zenith. Among the other sites Atacama shows the lower polarized signal at the zenith. We present maps of this signal for the various sites and show typical elevation and azimuth scans. We find that Dome C presents the lowest gradient in polarized temperature: ~ 0.3 {\mu}K/\circ at 90 GHz. We also study the frequency bands of observation: around {\nu} \simeq 100 GHz and {\nu} \simeq 160 GHz we find the best conditions because the polarized signal vanishes. Finally we evaluate the accuracy of the templates and the signal variability in relation with the knowledge and the variability of the Earth magnetic field and the atmospheric parameters.

Water vapor sounding with the far infrared REFIR-PAD spectroradiometer from a high-altitude ground-based station during the ECOWAR campaign

[1] The Radiation Explorer in the Far InfraRed-Prototype for Applications and Development (REFIR-PAD) spectroradiometer was operated from the Testa Grigia Italian-Alps station in March 2007 during the Earth Cooling by Water Vapour Radiation (ECOWAR) measurement campaign, obtaining downwelling radiance spectra in the 100–1100 cm−1 range, under clear-sky conditions and in the presence of cirrus clouds. The analysis of these measurements has proven that the instrument is capable of determining precipitable water vapor with a total uncertainty of 5–7% by using the far-infrared rotational band of water. The measurement is unaffected by the presence of cirri, whose optical depth can be instead retrieved as an additional parameter. Information on the vertical profiles of water vapor volume mixing ratio and temperature can also be retrieved for three altitude levels. The ability to measure the water vapor column with a simple, uncooled instrument, capable of operating continuously and with a time resolution of about 10 min, makes REFIR-PAD a very valuable instrument for meteorological and climatological studies for the characterization of the water vapor distribution.

A study of the galaxy redshift distribution towards the cosmic microwave background cold spot in the Corona Borealis supercluster

We present a study of the spatial and redshift distributions of Sloan Digital Sky Survey (SDSS) galaxies toward the position of CrB-H, a very deep and extended decrement in the Cosmic Microwave Background (CMB), located within the Corona Borealis supercluster (CrB-SC). It was found in a survey with the Very Small Array (VSA) interferometer at 33 GHz, with a peak negative brightness temperature of -230 muK, and deviates 4.4-sigma from the Gaussian CMB (G\'enova-Santos et al.). Observations with the Millimeter and Infrared Testa Grigia Observatory (MITO) suggested that 25$^+21_-18% of this decrement may be caused by the thermal Sunyaev-Zel'dovich (tSZ) effect (Battistelli et al.). Here we investigate whether the galaxy distribution could be tracing either a previously unnoticed galaxy cluster or a Warm/Hot Intergalactic Medium (WHIM) filament that could build up this tSZ effect. We find that the projected density of galaxies outside Abell clusters and with redshifts 0.05<z<0.12 at the position of CrB-H is the highest in the area encompassed by the CrB-SC. Most of these galaxies are located around redshifts z=0.07 and z=0.11, but no clear connection in the form of a filamentary structure is appreciable in between. While the galaxy distribution at z=0.07 is sparse, we find evidence at z=0.11 of a galaxy group or a low-mass galaxy cluster. We estimate that this structure could produce a tSZ effect of ~ -18 muK. The remaining VSA signal of ~ -212 muK is still a significant 4.1-sigma deviation from the Gaussian CMB. However, the MITO error bar allows for a larger tSZ effect, which could be produced by galaxy clusters or superclusters beyond the sensitivity of the SDSS. Contributions from other possible secondary anisotropies associated with these structures are also discussed.

Millimeter wave spectroscopic measurements of stratospheric and mesospheric constituents over the Italian Alps: stratospheric ozone

Measurements of rotational lines emitted by middle atmospheric trace gases have been carried out from the Alpine station of Testa Grigia (45.9°N, 7.7°E, elev. 3500 m) by means of a Ground-Based Millimeter-wave Spectrometer (GBMS). Observations of species such as O3, HNO3, CO, N2O, HCN, and HDO took place during 4 winter peri- ods, from February 2004 to March 2007, for a total of 116 days of measurements grouped in about 18 field cam- paigns. By studying the pressure-broadened shape of emission lines the vertical distribution of the observed con- stituents is retrieved within an altitude range of ∼17-75 km, constrained by the 600 MHz pass band and the 65 kHz spectral resolution of the back-end spectrometer. This work discusses the behavior of stratospheric O3 during the entire period of operation at Testa Grigia. Mid-latitude O3 columnar content as estimated using GBMS measure- ments can vary by large amounts over a period of very few days, with the largest variations observed in December 2005, February 2006, and March 2006, confirming that the northern winter of 2005-2006 was characterized by a particularly intense planetary wave activity. The largest rapid variation from maximum to minimum O3 column val- ues over Testa Grigia took place in December 2006 and reached a relative value of 72% with respect to the aver- age column content for that period. During most GBMS observation times much of the variability is concentrated in the column below 20 km, with tropospheric weather systems and advection of tropical tropospheric air into the lower stratosphere over Testa Grigia having a large impact on the observed variations in column contents. Nonethe- less, a wide variability is also found in middle stratospheric GBMS O3 measurements, as expected for mid-latitude ozone. We find that O3 mixing ratios at ∼32 km are very well correlated with the solar illumination experienced by air masses over the previous ∼15 days, showing that already at 32 km altitude ozone photochemistry dominates over transport processes. The correlation of lower stratospheric ozone concentrations with potential vorticity as an indi- cator of transport is instead not as clear-cut, due to very complex mixing processes that characterize stratospheric air at mid-latitudes. Correlations of O3 over Testa Grigia with stratospheric tracers such as N2O and HCN, also ob- served by means of the GBMS, are planned for the future, in order to better characterize lower stratospheric dy- namics and therefore lower stratospheric ozone concentrations at mid-latitudes.

Cosmic rays at High Mountain Observatories

The worldwide distribution of High Mountain Observatories provides a unique opportunity for performing contemporary measurements under different geomagnetic/altitude conditions and for collecting long-term data series. In this context, the history and some activities performed at two historical Research Stations are summarized: Chacaltaya Laboratory (Bolivia) and the Testa Grigia Research Station (Italy).

Millimeter Observation of the SZ Effect in the Corona Borealis Supercluster

We have observed the Corona Borealis supercluster with the Millimeter and Infrared Testa Grigia Observatory (MITO), located in the Italian Alps, at 143, 214, 272, and 353 GHz. We present a description of the measurements, data analysis, and results of the observations together with a comparison with observations performed at 33 GHz with the Very Small Array (VSA) interferometer situated at the Teide Observatory (Tenerife, Spain). Observations have been made in the direction of the supercluster toward a cosmic microwave background (CMB) cold spot previously detected in a VSA temperature map. Observational strategy and data analysis are described in detail, explaining the procedures used to disentangle primary and secondary anisotropies in the resulting maps. From a first level of data analysis, we find evidence in MITO data of primary anisotropy but still with room for the presence of secondary anisotropy, especially when VSA results are included. With a second level of data analysis using map making and the maximum entropy method, we claim a weak detection of a faint signal compatible with a SZ effect, characterized at most by a Comptonization parameter y = (7.8) × 10-6 68% CL. The low level of confidence in the presence of a SZ signal invites us to study this sky region with higher sensitivity and angular resolution experiments such as the already-planned upgraded versions of VSA and MITO.

MASTER: a radiometer for mm and sub-mm observations from the Antarctic Plateau

A radiometer based on SIS mixers for astrophysical observations is being assembled. The system, cooled to cryogenic temperature by a pulse tube refrigerator, is intended for operation on the Antartic Plateau during the local winter, using the mm dishes available there in the future. The system prototype will be tested at the focus of the 2.6 m MITO telescope at the Testa Grigia Observatory on the italian Alps. We discuss the system characteristics and the observational programs.

CMB Polarimetry from the Antarctic Plateau

The Milano Polarimeter (MiPol), a correlation system with phase modulation has been built for the studies of the CMB polarization at large angular scales. At present the system is at the Testa Grigia Observatory on the Italian Alps (3480 m asl). We are ready to bring it to Dome Concordia for observations during the Antarctic winter beginning in March 2006. We discuss the system performance, its sensitivity and the status of the searches for CMB polarization.

Triple Experiment Spectrum of the Sunyaev-Zel'dovich Effect in the Coma Cluster: H 0

The Sunyaev-Zel'dovich (SZ) effect was previously measured in the Coma Cluster by the Owens Valley Radio Observatory and Millimeter and IR Testa Grigia Observatory experiments and recently also with the W ilkinson Microwave Anisotropy Probe satellite. We assess the consistency of these results and their implications on the feasibility of high-frequency SZ work with ground-based telescopes. The unique data set from the combined measurements at six frequency bands is jointly analyzed, resulting in a best-fit value for the Thomson optical depth at the cluster center, τ0 = (5.35 ± 0.67) × 10-3. The combined X-ray and SZ determined properties of the gas are used to determine the Hubble constant. For isothermal gas with a β density profile we derive H0 = 84 ± 26 km (s Mpc)-1; the (1 σ) error includes only observational SZ and X-ray uncertainties.

Calibration and first light of the Diabolo photometer at the Millimetre and Infrared Testa Grigia Observatory

We have designed and built a large-throughput dual channel photometer, Diabolo. This photometer is dedicated to the observation of millimetre continuum diffuse sources, and in particular, of the Sunyaev-Zel'dovich effect and of anisotropies of the 3K background. We describe the optical layout and filtering system of the instrument, which uses two bolometric detectors for simultaneous observations in two frequency channels at 1.2 and 2.1 mm. The bolometers are cooled to a working temperature of 0.1 K provided by a compact dilution cryostat. The photometric and angular responses of the instrument are measured in the laboratory. First astronomical light was detected in March 1995 at the focus of the new Millimetre and Infrared Testa Grigia Observatory (MITO) Telescope. The established sensitivity of the system is of 7 mK_RJ s^1/2$. For a typical map of at least 10 beams, with one hour of integration per beam, one can achieve the rms values of y_SZ ~ 7 10^-5 and the 3K background anisotropy Delta T/T ~ 7 10^-5, in winter conditions. We also report on a novel bolometer AC readout circuit which allows for the first time total power measurements on the sky. This technique alleviates (but does not forbid) the use of chopping with a secondary mirror. This technique and the dilution fridge concept will be used in future scan--modulated space instrument like the ESA Planck mission project.

High-performance wobbling subreflector for the Millimetre and Infrared Testa Grigia Observatory 26-m telescope

The Millimetre and Infrared Testa Grigia Observatory 2.6-m Cassegrain telescope has been designed to allow high-sensitivity observations in the millimeter spectral range. For this purpose, in order to reduce unwanted contributions from local foregrounds, we adopted a sky-chopping technique, by wobbling the telescope subreflector. We describe the design and performance of the wobbling system, which can endure external forced two and three fields square-wave modulation and includes features such as high frequency, high amplitude, high duty cycle, low microphonics, and high stability.

MITO: a procedure for CBA measurements and a search for cosmic strings

MITO (Millimetric and Infrared Testa Grigia Observatory) is a 3 m telescope dedicated to the study of Cosmic Background Anisotropies. It is located at 3500 m above sea-level at Plateau Rosa, Cervinia. We describe the Observatory and discuss two on-going research programs: a clearning procedure in order to remove galactic dust signals from cosmological data and a search for cosmic strings toward double-lensed quasars. Both the programs will be carried out by means of a He-3 photometer operating at the frequencies of 5, 10, 12, 30 cm−1.

Infrared limit on the fine-scale anisotropy of the cosmic background radiation

The cosmic-background anisotropy has been investigated at the angular scale of 25 minutes of arc by means of a special isotropometer at the alpine station of Testa Grigia (3500 m above sea level) through the atmospheric window 1.0-1.4 mm. We found an upper limit $\frac{\ensuremath{\Delta}T}{T}\ensuremath{\lesssim}1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ at two standard deviations. Some physical implications about the origin and the rotation of superclusters and about the secondary ionization of plasma are discussed.

Atmospheric transmittance in the far infrared at Testa Grigia

Atmospheric transmittance in the band of 300–2000 μm was measured in the far i.r. Solar Observatory of Testa Grigia, 3480m above standard. These measurements are compared with the meteorological data observed at Plateau Rosa in the last 7yr.