Search

The δ 13 C profile of Globigerinoides ruber , measured in the GT90/3 shallow-water Ionian sea core and dated with high precision, is presented and analyzed using the Singular Spectrum Analysis and the Wavelet Transform. This time series covers the period 200–1979 AD, with a resolution of 3.87 years. The δ 13 C of foraminifera depends on the photosynthetic activity of the symbiontic algae living on the shells, strictly related to the illumination of the sea-surface. Both spectral methods, besides an 11-years oscillation in phase with the Schwabe cycle of the solar activity, show the presence of a centennial cycle that is in phase with the amplitude modulation of the sunspot number series in the last 300 years. Moreover, another climatic record, the tree ring δ 13 C of a Japanese cedar covering the time interval 125–1952 AD, shows a similar centennial oscillation and therefore suggests that this climatic variation is global and in phase with the solar activity.

Extensive Air Showers at large zenith angles θ > 70° (Horizontal Air Showers, HAS) are observed at the EAS-TOP array at Campo Imperatore (Gran Sasso Laboratories). The rate of these events exceeds the one due to primary cosmic rays (at this angles) and therefore these showers have to be generated by penetrating particles. Assuming that they are produced by atmospheric muons we derived the muon flux as Fμ(> 30 TeV) = 1.1 × 10−11cm−2s−1sr−1, in good agreement with the underground measurements. The upper limits for diffuse neutrino radiation from these measurements is Iν(> 105GeV) dI ν e (E 0 )/dE ν e −18 cm −2 s −1 sr −1 GeV −1 , for the resonant ( E 0 = m W 2 2m e = 6.4 × 10 6 GeV ) neutrinos.

The evolution of the cosmic ray primary composition in the energy range 10 6 –10 7 GeV (i.e. the “knee” region) is studied by means of the e.m. and muon data of the Extensive Air Shower EAS-TOP array (Campo Imperatore, National Gran Sasso Laboratories). The measurement is performed through: (a) the correlated muon number ( N μ ) and shower size ( N e ) spectra, and (b) the evolution of the average muon numbers and their distributions as a function of the shower size. From analysis (a) the dominance of helium primaries at the knee, and therefore the possibility that the knee itself is due to a break in their energy spectrum (at E k He =(3.5±0.3)×10 6 GeV) are deduced. Concerning analysis (b), the measurement accuracies allow the classification in terms of three mass groups: light (p,He), intermediate (CNO), and heavy (Fe). At primary energies E 0 ≈10 6 GeV the results are consistent with the extrapolations of the data from direct experiments. In the knee region the obtained evolution of the energy spectra leads to: (i) an average steep spectrum of the light mass group ( γ p,He >3.1), (ii) a spectrum of the intermediate mass group harder than the one of the light component ( γ CNO ≃2.75, possibly bending at E k CNO ≈(6–7)×10 6 GeV), (iii) a constant slope for the spectrum of the heavy primaries ( γ Fe ≃2.3–2.7) consistent with the direct measurements. In the investigated energy range, the average primary mass increases from 〈ln A 〉=1.6–1.9 at E 0 ≃1.5×10 6 GeV to 〈ln A 〉=2.8–3.1 at E 0 ≃1.5×10 7 GeV. The result supports the standard acceleration and propagation models of galactic cosmic rays that predict rigidity dependent cut-offs for the primary spectra of the different nuclei. The uncertainties connected to the hadronic interaction model (QGSJET in CORSIKA) used for the interpretation are discussed.

UHE cosmic rays are studied by means of the detectors of the different components of secondaries produced by their interactions in the atmosphere (EAS). We describe and discuss the reconstruction techniques and accuracies of the e.m. detector of EAS-TOP. They allow, besides independent high resolution measurements of UHE γ-ray astronomy, good correlation possibilities with the detectors of the different EAS components.

A search for transient point sources of ultra-high-energy (UHE) γ-rays has been performed, based on the correlation of two extensive air shower arrays, BAKSAN (North Caucasus, 1700 m a.s.l., BAKSAN Neutrino Observatory, Russia) and EAS-TOP (Campo Imperatore, 2005 a.s.l., Laboratori Nazionali del Gran Sasso, Italy), which are located at very similar latitudes (φ≈43° N), and separated in longitude by Δλ≈33.7°. The search has been conducted at primary energy Eγ⩾5×1013 eV on the time scale of a daily source transit over the sky, observable in the northern hemisphere (19° The stability of the single detectors has been studied and verified up to high significance level. No coincident excess, not compatible with the expectations from statistical fluctuations, has been observed. The obtained upper limits to the rate of transient events, nγ, at 90% c.l., are • concerning the sky survey, in the declination band corresponding to the zenith, n γ /(Ωt) /(yr sr) with Φγ(Eγ>5×1013 eV)>2.0×10−11 cm −2 s−1 and duration Δt • concerning the candidate sources, e.g., for Markarian 421: nγ/t 5×1013 eV)>1.3×10−11 cm −2 s−1 and Δt A coincident episode from Markarian 421, observed on 15 January, 1994, with expected chance imitation rate nch= 0.01 is discussed.

The break observed in the electron shower size power law spectrum of Extensive Air Showers (EAS) at corresponding primary energy E-0 similar to (3 - 5)10(15) eV ("knee") is studied in different EAS components (electromagnetic and muonic) and at different atmospheric depths. A consistent description is obtained. The interpretation of data in terms of primary composition, and following the most accepted high energy interaction models, leads to an increasing average primary mass in this energy range. The study of such behaviour is expected to provide a crucial information for the understanding of the physical parameters that characterize the break for the different primaries.

The cross section for large p t jet production for transverse momentum 10≤ p t ≤20 GeV/c and rapidity 1.6≤ η ≤2.6 in p – N ( p –`air') interactions is studied from the analysis of multicore Extensive Air Showers recorded in the EAS–TOP calorimeter. The projectiles are the leading particles interacting at atmospheric depths between 250 and 480 cm −2 , the CMS energy of interaction being s ≈500 GeV. The slope of the p t distribution agrees with the expected one from the p – p collider data at the same CMS energy. The measured jet production cross section in p – N interactions with respect to p – p interactions is (dσ/dp t ) pN jet =(dσ/dp t ) p p jet ·A α with α =1.56±0.07 for A =14.7 (average mass number of `air' nuclei). Such value is compatible within the experimental uncertainties with the one obtained in p –nucleus accelerator measurements at s ≃30 GeV in the same range of transverse momentum and rapidity. No indication of increase of α with energy, i.e. of the entity of the `Cronin effect', is found.

The amplitude and phase of the first harmonic of the sidereal anisotropy of cosmic rays at E 0 = 2·10 14 eV have been measured by the EAS-TOP experiment (Campo Imperatore, 2005 m a.s.l., LNGS, Italy) and are respectively (at the equatorial plane): A sid = (3.73±0.57)·10 −4 ; φ sid = 1.82±0.49 h lst, with significance 6.5 s.d. The result is supported by different consistency checks. From the comparison with lower energy data, it follows that the amplitude and the phase of the cosmic ray anisotropy are constant over the energy range 10 12 – 2·10 14 eV. This implies at these energies a constant influence of the local interstellar medium on the propagation of cosmic rays.

The cosmic ray energy spectrum in the range E-o = 10(15)-10(16) eV (including the region of the steepening, "knee") is studied by means of the EAS-TOP array (Campo Imperatore, Gran Sasso Laboratories, atmospheric depth 820 g cm(-2)). Measurements of the electromagnetic size (N-e = total number of charged particles at the observation level) are performed as a function of zenith angle with statistical accuracies of a few percent. The change of slope of the spectrum is observed in each bin of zenith angle at size values decreasing with increasing atmospheric depth. Its attenuation is compatible with the one of shower particles (Lambda(e) = 219 +/- 3 g cm(-2)). This observation provides a consistency check, supporting a normal behaviour of showers at the break, that make plausible astrophysical interpretations based on an effect on primaries occurring at a given primary energy. The break has a "sharp" shape (i.e., within experimental errors is compatible with two intersecting power laws) that represents a constraint with which any interpretation has to match. The change of slope of the power law index reproducing the size spectrum is Delta gamma = 0.40 +/- 0.09. The derived all particle energy spectrum is in good agreement with the extrapolation of the direct measurements at low energies and with other EAS data at and above the knee. Power laws fits to the energy spectrum below and above the knee give tin units of m(-2) s(-1) sr(-1) TeV-1) S(E-o) = (3.48 +/- 0.06) x 10(-10) (E-o/2300)(-2.76+/-0.03) for 900 TeV < E-o < 2300 TeV and S(E-o) = (3.77 +/- 0.08) x 10(-11) (E-o/5000)(-3.19+/-0.06) for 5000 TeV < E-o < 10(4) TeV. The systematic uncertainties connected to the interaction model and the primary composition are discussed. (C) 1999 Elsevier Science B.V.

We have previously shown that the very low activity of the cosmogenic 44Ti in meteorites records the galactic cosmic ray (GCR) flux over a century time-scale (Bonino et al., 1995). The heliospheric magnetic field (HMF) variations are the principal source of the GCR modulation in the heliosphere. We present here new measurements which extend our investigation over the last two centuries. The 44Ti activity at the time of fall has been obtained on the basis of the recently revised value of its half-life of 59.2 years. We basically confirm our earlier findings (Bonino et al., 1997). The 44Ti profile, with the time of fall of the meteorites, shows variations in phase in agreement with those expected. The magnitude of oscillations is ∼ 4 times higher than expected (∼ 6%) on the basis of the GCR flux over the past centuries deduced from sunspot number since 1700 and by the neutron monitor and balloon measurements in the last decades. The higher 44Ti production rate during prolonged solar quiet periods (Gleissberg minima) may imply that during these minima the HMF was weaker than during the recent minima of the 11-year solar cycle.

We tested the effects of daily melatonin treatment on the growth of the ascites hepatoma in rats, determining survival time, cell number and cell cycle phases at various stages of tumor development. Melatonin inhibited cellular proliferation, doubled mean life-time and increased survival. Thymidine incorporation in hepatoma cells from treated rats decreased significantly without changes in the apoptotic index. Flow cytometric analysis showed that melatonin slowed cell cycle progression by increasing the number of cells in phase G0G1. Thus, similar to in vitro models, melatonin's oncostatic action in vivo appears to be directed to specific cell cycle mechanisms, which remain to be elucidated.

Production of cosmogenic radioisotopes in meteorites depends on the galactic cosmic ray flux, which is controlled by the heliospheric magnetic field (HMF), which, in turn, depends on the solar activity. The radioisotopes can, therefore, serve as proxy records of the behaviour of the heliosphere in the past, in particular over prolonged solar quiet periods, such as during Gleissberg or Maunder minima, when the production rate of radioisotopes is expected to change significantly. For this purpose we have measured the 44 Ti (T 1/2 =66.6 yr) in ten stony meteorites, which fell between 1840–1992. The results indicate that the production of 44 Ti was significantly higher when the solar activity was persistently low, indicating that the HMF was weak during such periods, enabling higher flux of cosmic rays to enter the inner heliosphere.

A number of marine as well as continental K/T sections in India, particularly around the Deccan volcanic regime, have been analyzed to obtain concentration profiles of some platinum group and other trace elements, specifically to search for anomalous levels of iridium. Except for the Um Sohryngkew River (USR) section in Meghalaya, where iridium is found to occur at an anomalously high level in the K/T boundary layer, all other sections show low levels in the range of 10 to ∼120 pg/g. The iridium profile in the USR section is characterized by a sharp peak of 12.1 ng/g in a 1.5 cm thick limonitic layer, superimposed on a broad band of ∼0.2 ng/g extending over a 50±20 cm thick section, beyond which Ir decreases to the base level of ∼0.02 ng/g, both in the Tertiary as well as in the Cretaceous. High Ir is accompanied by high Os but the Os/Ir ratio in the peak (0.37) is different from the Os/Ir ratio of ∼2 measured in the broad band. The Ir profile in the USR section seems to be consistent with fallout of cometary debris preceding and following the main impact. The measurements at other sites in the Deccan suggest that the iridium inventory of the Deccan is too low to account for the high iridium observed in the KTB layer all over the world, but may be sufficient to give rise to its enhancement adjacent to the KTB peak.

A study was performed in Yoshida hepatoma-bearing rats to confirm in vivo, in an experimental model, the preliminary data on the potentiation by lonidamine of the antitumor activity of adriamycin. Lonidamine alone, administered orally with food, did not reduce tumor cell proliferation, but in combination with adriamycin (5 mg/kg intraperitoneally 6 days after tumor transplant), it produced a remarkable increase in adriamycin's hepatoma cell toxicity (44% vs controls, P P

In the energy region 10 - 100 TeV both the c.r. composition from direct measurements and the cross section for high energy secondary production in the very forward region for p-air interactions are rather uncertain. Contemporaneous measurements of the total energy and of the threshold energy/nucleon of the primary particle can be provided by the atmospheric Cherenkov light and high energy muons. These measurements are performed by the combined operation of the Cherenkov array of the EAS-TOP experiment on the surface (810 gcm(2) atmospheric depth) and of the LVD experiment in the underground Gran Sasso Laboratories (3300 m w.e.; E-mu(th) = 1.3 TeV) leading to the measurement of < N-mu > (E-mu > 1.3 TeV, E-o) in the given energy range. The combined operation of the experiments and preliminary results are reported.

The attenuation length of proton primaries and the proton-air inelastic cross section are studied at energies E 0 ≈ 10 15 eV by using the EAS-TOP array data. Proton initiated Extensive Air Showers, in the energy range (2 ÷ 4) 10 15 eV and near maximum development, are selected from their N μ ( E μ > 1 GeV) and N e sizes. The experimental attenuation length A obs is compared with those obtained from simulations, including the full detector response. based on different interaction models (HDPM, VENUS, DPMJET, QGSJET and SIBYLL) in the frame of CORSIKA code. The proton-air inelastic cross section is also inferred by using the factor k = Λ obs sim /λ p —air sim obtained from each interaction model.

Horizontal Air Showers, i.e. events observed at “quasi” horizontal incidence, are studied from EAS-TOP at Campo Imperatore (National Gran Sasso Laboratories). The “reality” of such events as due to deeply penetrating particles is discussed from the experimental point of view. We deduce: • -the measurement of the HE muon flux at E μ = 20 TeV : F μ (> 20 TeV ) = (1.3 ± 0.4) × 10 −11 cm −2 s −1 sr −1 , • -the upper limit to the extraterrestrial HE neutrino flux: I ν (> 10 5 GeV ) −9 cm −2 s −1 sr −1 . • The possibility to develop the technique for UHE ν detection is discussed.

The recent data on the EAS size spectrum, and on the rate of ‘Horizontal Air Showers’ (HAS), as detected by the EAST-TOP experiment at Campo Imperatore (LNGS), are presented. Their implications for the interpretation of underground muon data, and for UHE neutrino astronomy are discussed.

The detector of the e.m. component of Extensive Air Showers of the EAS-TOP array at Gran Sasso has been in operation for part of 1988 and 1989. We present the results obtained at primary energy Eγ ≈ 150 TeV in the study of the candidate sources observable in the northern emisphere. The observations of Cygnus X-3 during the radio burst of June '89 are discussed.

The characteristics of the EAS-TOP extensive air shower array as a detector of very high energy cosmic rays ( E 0 ≥ 10 14 eV) for astrophysical studies are discussed. The array is located on top of the underground Gran Sasso Laboratory in central Italy; a subarray (11 modules of the em detector) has been operating since the end of 1987. From such data the stability of the detector, the timing resolution, the accuracies in the determination of the arrival directions ( δθ = 1.2° at E 0 ∼ 200 TeV in the present configuration) and in the reconstruction of the lateral electron distribution and of the shower size are derived.

In order to investigate the extent to which 10Be concentrations in polar ice record solar activity on the level of individual Schwabe solar cycles, we have measured 10Be concentrations over the interval from 1180 to 1800 A.D. in an ice core from Greenland, using the accelerator mass spectrometer of the ETH Zurich. The data were analysed using the cyclogram method of time series analysis which showed that 10Be concentrations varied with a period which ranged between 9 and 11.4 y. Schwabe-type 10Be variations were visible even during the Maunder Minimum (1645–1715 A.D.), an interval of almost no visible sunspots. During this period 10Be concentrations varied with a periodicity which slowly increased from 9 to 11 y. 10Be concentrations were higher during the Maunder Minimum than during minima in the 11 y Schwabe cycle. This suggests the presence of residual solar modulation even during Schwabe solar cycle minima.

LVD is a large volume detector which will be installed in Hall A of the Gran Sasso Laboratory. This detector is 49 m long, 13.2 m high and 12 m wide. It contains 2280 m3 of scintillator (1800 t) and 1800 t of steel. The geometric acceptance of LVD for an isotropic flux of particles is greater than 7000 m2 sr. LVD is the ideal detector for detecting a stellar collapse, anywhere in our galaxy; for studying neutrino oscillations; for searching for the supersymmetric decay mode of the proton; and for looking at the boron neutrinos from the sun. LVD is a very competitive detector for detecting astrophysical neutrino emitting point sources, for performing dark matter searches, for studying single muon distributions, for detecting muon bundles and hence determining the primary cosmic ray composition, and for searching for massive monopoles and other ultra heavy particles. LVD is composed of 190 identical modules, of which the first 10% of these modules will installed in 1987.

The large-volume detector (LVD) which will be installed in Hall A of the Gran Sasso Laboratory can be defined as an underground observatory devoted to neutrino astronomy and to the measurement of the penetrating components of cosmic rays. The detector consists of two major parts: the tracking system and the scintillator system. It is specifically designed to permit a multipurpose experiment allowing the detection of neutrino interaction inside the detector and the detection of omnidirectional mu-mesons and the measurement of their trajectories and direction of flight.

The self-diffusion coefficient of CH 4 has been measured at temperatures around the critical temperature T c by the capillary technique. An anomaly of (80 ± 20)% has been observed within ±0.25 K of T c .

The self diffusion coefficient of carbon monoxide in the liquid phase has been measured in the range of temperature 69 to 78°K at a pressure of 70 cm Hg. The results are discussed by means of the corresponding states principle. It is found that CO behaves like a perfect liquid with regard to diffusion.