Cosmic rays for solar-terrestrial physics

Aspects of the research program conducted over the 1991-94 period by the CNR/IFSI project on Cosmic Rays in the Heliosphere are reviewed. Recent findings related to the solar-interplanetary-terrestrial chain are discussed

Archeologia e letteratura. Senso dell’antico nella narrazione italiana contemporanea

Partendo dal romanzo di Matilde Serao, "La conquista di Roma", pubblicato nel 1885, il saggio ricostruisce le modalità con cui la narrativa italiana prodotta in età contemporanea coniuga la memoria del passato con la sopravvivenza archeologica dell’antico, interrogandosi sul valore che la menzione delle vestigia storiche riveste agli occhi del narratore e, presumibilmente, del pubblico al quale si rivolge. Si susseguono così un’analisi del "Piacere" di D’Annunzio, del "Fu Mattia Pascal" di Pirandello, non senza ricordare la posizione espressa da un poeta come Ungaretti in "Interpretazione di Roma", del 1954, per chiudere con il più recente romanzo noir, "Un giorno perfetto" (2005) di Melania Mazzucco. Utilizzando le categorie critiche dell’antropologo della surmodernità Marc Augé, l’analisi finisce così con il dar conto delle forme con cui la rappresentazione della città storica si trasforma nell’immagine di un moderno non luogo, spazio abitato da identità sospese, in cui il nuovo minaccia e sommerge l’antico

Anomalous short-term increases in the galactic cosmic ray intensity: Are they related to the interplanetary magnetic cloud-like structures?

Thirty-one short-term increases (time duration 24 hours and amplitude up to 5%) in the galactic cosmic ray intensity, occurring inside Forbush decreases events, have been identified over the period 1966 - 1977. These increases are highly anisotropic and occur after the compression region following the shock; the interplanetary medium is characterized by intense ( 10 nT) and higly fluctuating magnetic field B, high velocity, low density and temperature (flare ejecta piston?). These B-fluctuations seem to be ordered variations which could be representative of magnetic clouds. Also the large cosmic ray increase occurring on 17-18 September 1979, belongs to this category of events

The green corona data: 1947-1976, revisited

Re-examining a continuous monthly data set for the green-line corona brightness, covering February 1947 to September 1976, we have found that practically no delay exists between the trends of the green-line coronal intensity in the equatorial and middle-latitude belts at the beginning of solar activity cycle No. 20, while a previous cycle (No. 19) shows a sudden increase in the corona intensity brightness at middle latitudes followed by a delayed one at the equatorial belts, supporting recent findings on even-odd solar cycle differences observed in the half-yearly green corona database (1943-1993). The north-south asymmetry in the hemispheric solar activity is not involved in this phenomenon

The flare origin of Forbush decreases not associated with solar flares on the visible hemisphere of the Sun

Investigations have shown that Forbush decreases (Fds) are produced by the propagation into the interplanetary space of a strong perturbation originating from a solar flare (Sf) accompanied by Type IV radioemission. As the front of the perturbation propagates into the interplanetary space, the region in which the galactic cosmic rays are modulated (Fd-modulated region) rotates westward with the Sun and is generally included between two boundary streams; therefore the Fds not associated with observed type IV Sfs (N.Ass.Fds) are likely to be produced by type IV Sfs occurred on the Sun's backside: these vents can be observed when the Earth crosses the corotating Western boundary of the modulated region

Longitudinal dependence of the interplanetary perturbation produced by energetic type 4 solar flares and of the associated cosmic ray modulation

One of the most significant features of the flare-associated Forbush decreases (Fds) in the galatctic cosmic ray (c.r.) is the so-called East-West asymmetry: the solar flares (Sfs) observed in the Eastern or central region of the solar disk exhibit a higher probability to cause large Fds than the Sfs occurring in the Western portion of the disk. In particular the interplanetary perturbations generated by Type IV Sfs depress the c.r. intensity in a vast spiral cone-like region (modulated region) which extends along the interplanetary magnetic field from the neighborhood of the active region to the advancing perturbation, and that, immediately after the flare-generated perturbation, the maximum c.r. modulation is observed between 0 and 40 deg. W of the meridian plane crossings the flare site at time of flare (flare's meridian plane)

Suggestions for improving the efficiency of ground-based neutron monitors for detecting solar neutrons

On the occasion of the June 3, 1982 intense gamma-ray solar flare a significant increase in counting rate due to solar neutrons was observed by the neutron monitors of Junsfraujoch and Lomnicky Stit located at middle latitudes and high altitudes. In spite of a larger detector employed and of the smaller solar zenith angle, the amplitude of the same event observed at Rome was much smaller and the statistical fluctuations of the salactic cosmic ray background higher than the ones registered at the two mountain stations, because of the greater atmospheric depth at which the Rome monitor is located. The effeciency for detecting a solar neutron event by a NM-64 monitor as a function of the Sun zenith angle, atmospheric depth and threshold rigidity of the station was studied