S. Vernetto

Muon ''depth-intensity'' relation measured by the LVD underground experiment and cosmic-ray muon spectrum at sea level

We present the analysis of the muon events with all muon multiplicities collected during 21804 hours of operation of the first LVD tower. The measured angular distribution of muon intensity has been converted to the `depth -- vertical intensity relation in the depth range from 3 to 12 km w.e.. The analysis of this relation allowed to derive the power index,

High-energy cosmic-ray physics with an EAS array on the top of the Gran Sasso Laboratory

gamma

Measurement of the cosmic ray hadron spectrum up to 30-TeV at mountain altitude: The Primary proton spectrum

, of the primary all-nucleon spectrum:

Muon sea-level intensity and primary cosmic-ray nucleon spectrum in the (1÷100) TeV energy range from the Mt. Blanc underground experiment

gamma=2.78 pm 0.05

Limits on low-energy neutrino fluxes with the Mont Blanc liquid scintillator detector

. The `depth -- vertical intensity relation has been converted to standard rock and the comparison with the data of other experiments has been done. We present also the derived vertical muon spectrum at sea level.

The large-volume detector (LVD) of the Gran Sasso Laboratory

SummaryAn air shower array on top of the underground Gran Sasso Laboratory (GSL) can give valuable information in the field of high-energy cosmic-ray physics. We discuss the performances of a specific apparatus (EAS-TOP) operating both in coincidence with the underground array (i.e. for measuring the total primary energy of multimuon events) and as an autonomous air shower detector (for studies of ultra-high-energy gamma-ray astronomy, cosmic-ray anisotropies and primary composition).RiassuntoUn apparato per EAS posto in superficie nella zona sovrastante il laboratorio sotterraneo del Gran Sasso può fornire utili informazioni sulla radiazione cosmica primaria. Qui si presenta un apparato (EAS-TOP) the funzionerà sia in coincidenza con gli apparati posti nel tunnel per misure sullenergia primaria degli eventi multimuonici sia in modo autonomo come rivelatore EAS per ricerche di γ-astronomia ad energie molto elevate, di anisotropia dei raggi cosmici primari, e di composizione primaria.РезюмеУстановка для регистрации ШАЛ над подземной лабораторией Гран Сассо может дать полезную информацию для физики космических лучей высоких энергий. Мы обсуждаем возможности установки EAS-TOP, работающей как в совпадении с подземными детекторами (для измерения полной начальной энергии в многомюинных событиях), так и в автономном режиме—для исследований в области гамма-астрономии сверхвысоких энергий, измерений анизотропии космических лучей и химического состава первичного излучения.

Energy spectrum and angular distribution of prompt cosmic-ray muons

Abstract The flux of cosmic ray hadrons at the atmospheric depth of 820 gxa0cm−2 has been measured by means of the EAS-TOP hadron calorimeter (Campo Imperatore, National Gran Sasso Laboratories, 2005 m a.s.l.). The hadron spectrum is well described by a single power law: S h (E h )=(2.25±0.21±0.34 sys )×10 −7 E h 1000 (−2.79±0.05) m −2 s −1 sr −1 GeV −1 overthe energy range 30 GeV–30 TeV. The procedure and the accuracy of the measurement are discussed. The primary proton spectrum is derived from the data by using the CORSIKA/QGSJET code to compute the local hadron flux as a function of the primary proton spectrum and to calculate and subtract the heavy nuclei contribution (basing on direct measurements). Over a wide energy range E0=0.5–50 TeV its best fit is given by a single power law: S(E 0 )=(9.8±1.1±1.6 sys )×10 −5 E 0 1000 (−2.80±0.06) m −2 s −1 sr −1 GeV −1 The validity of the CORSIKA/QGSJET code for such application has been checked using the EAS-TOP and KASCADE experimental data by reproducing the ratio of the measured hadron fluxes at the two experimental depths (820 and 1030 gxa0cm−2 respectively) at better than 10% in the considered energy range.The flux of cosmic ray hadrons at the atmospheric depth of 820 g/cm^2 has been measured by means of the EAS-TOP hadron calorimeter (Campo Imperatore, National Gran Sasso Laboratories, 2005 m a.s.l.). The hadron spectrum is well described by a single power law : S(E_h) = (2.25 +- 0.21 +- 0.34(sys)) 10^(-7)(E_h/1000)^(-2.79 +- 0.05) m^(-2) s^(-1) sr^(-1) GeV^(-1) over the energy range 30 GeV-30 TeV. The procedure and the accuracy of the measurement are discussed. The primary proton spectrum is derived from the data by using the CORSIKA/QGSJET code to compute the local hadron flux as a function of the primary proton spectrum and to calculate and subtract the heavy nuclei contribution (basing on direct measurements). Over a wide energy range E_0 = 0.5-50 TeV its best fit is given by a single power law : S(E_0) = (9.8 +- 1.1 +- 1.6(sys)) 10^(-5) (E_0/1000)^(-2.80 +- 0.06) m^(-2) s^(-1) sr^(-1) GeV^(-1). The validity of the CORSIKA/QGSJET code for such application has been checked using the EAS-TOP and KASCADE experimental data by reproducing the ratio of the measured hadron fluxes at the two experimental depths (820 and 1030 g/cm^2 respectively) at better than 10% in the considered energy range.

The limit to the UHE extraterrestrial neutrino flux from the observations of horizontal air showers at EAS-TOP

SummaryWe have measured the muon intensity underground up to 7100 hg/cm2 s.r. by means of a spark chamber apparatus. These intensities have been converted to a sea-level muon energy spectrum. An accurate description of the flux of hadrons and muons in the atmosphere allows us to derive the primary nucleon spectrum. If the validity of the superposition model and scaling in the fragmentation region is assumed, we find that the all nucleon spectrum is represented by a single exponent over the whole energy range (1°100) TeV and is given by the relationN(E)dE=(4.85±0.25)E−(2.79±0.04)dE.Riassuntoè stata misurata lintensità muonica fino alla profondità di 7100 hg/cm2 con un apparato a camere a scintilla. Queste intensità sono state convertite allo spettro denergia dei muoni al livello del mare, da cui unaccurata descrizione del flusso degli adroni e muoni in atmosfera permette di derivare lo spettro dei nucleoni primari. Assumendo la validità del modello di sovrapposizione e dello scaling nella regione di frammentazione, si trova che tutto lo spettro nucleonico è caratterizzato da un singolo esponente su tutto lintervallo denergia (1°100) TeV, ed è ben rappresentato dalla relazione (N(E)=(4.85±0.25)E−(2.79±0.04)dE.

Upper limit on the prompt muon flux derived from the LVD underground experiment

Abstract The LSD liquid scintillation detector has been operating since 1985 as an underground neutrino observatory in the Mont Blanc Laboratory with the main objective of detecting antineutrino bursts from collapsing stars. In August 1988 the construction of an additional lead and borex paraffin shield considerably reduced the radioactive background and increased the sensitivity of the apparatus. In this way the search for steady fluxes of low-energy neutrinos of different flavours through their interactions with free protons and carbon nuclei of the scintillator was made possible. No evidence for a galactic collapse was observed during the whole period of measurement. The corresponding 90% c.l. upper limit on the galactic collapses rate is 0.45 y −1 for a burst duration of ΔT ⩽ 10 s. After analysing the last 3 years data, the following 90% c.l. upper limits on the steady neutrino and antineutrino fluxes were obtained: Φ( gn e ) 4 gn e s −1 cm −2 9 ⩽ E ν ⩽ 50MeV Φ( gn e ) 3 gn e s −1 cm −2 20 ⩽ E ν ⩽ 50MeV Φ(ν e ) 3 ν e s −1 cm −2 25 ⩽ E ν ⩽ 50 MeV Φ(ν μ + τ ) 7 ν μ + τ s −1 cm −2 20 ⩽ E ν ⩽ 100 MeV Φ( gn μ + τ ) 7 gn μ + τ s −1 cm −2 20 ⩽ E ν ⩽ 100 MeV In particular comparing the obtained upper limit on the gn e flux for 9 ⩽ E ν ⩽ 20 MeV to the solar ν e flux predicted by the standard solar model in the same range of energy, we can exclude the possibility that more than 6.3% of the solar ν e s flux can change to gn e . Finally the first limits on the flux of relic supernova neutrinos of all flavours as a function of the neutrino sea temperature are presented.

Primary cosmic-ray spectrum at energies ∼(1013÷1016) eV from multiple muon events in NUSEX experiment

SummaryWe describe here the LVD experiment (Large-Volume Detector) of the Gran Sasso Laboratory, which is the natural improvement of the LSD experiment (Liquid Scintillation Detector) running in the Mont Blanc Laboratory. The LVD ((31×13) m2 area, height 12 m) consists of ≈1800 tons of liquid scintillator and of a system of streamer tubes on 5 layers for reconstructing tracks of charged particles. As any experiment in an underground laboratory, which has a low statistics of events and requires long running times, the LVD is a multipurpose experiment but with different priorities of the researches. The main goal is neutrino astronomy, firstly detection of neutrinos from collapsing stars and secondly high-energy neutrinos and solar neutrinos. Since the expected number of interactions of neutrinos, from a stellar collapse is very high (of order of 900 for a collapse at the distance of the galactic centre), the LVD is, contrary to the present experiments, a real neutrino observatory, able to make a detailed analysis of the energy and temporal distributions of the burst. In addition to neutrino astrophysics, with the LVD experiment excellent possibilities exist to perform researches in cosmic-ray and high-energy elementary-particle physics.RiassuntoSi descrive lesperimento LVD (Large Volume Detector) del laboratorio del Gran Sasso, che rappresenta il naturale sviluppo dellesperimento LSD (Liquid Scintillation Detector) in funzione nel laboratorio del Monte Bianco. LVD (area (31×13) m2, altezza 12 m) consiste di ∼1800 tonnellate di scintillatore liquido e di un sistema di tubi a streamer su 5 piani per la ricostruzione delle tracce di particelle cariche. Come tutti gli esperimenti in laboratori sotterranei, che sono a tempi lunghi ed a bassa statistica, lesperimento LVD è a multiscopi ma con diverse priorità delle ricerche. Lobiettivo principale è lastronomia neutrinica, in primo luogo la rivelazione di neutrini da collassi gravitazionali stellari, e poi neutrini di alta energia e neutrini solari. Dato lalto numero previsto di interazioni di neutrini (∼900 per un collasso alla distanza del centro galattico) da stelle collassanti, lesperimento LVD costituisce, a differenza degli attuali esperimenti, un vero e proprio osservatorio neutrinico, in grado di compiere unanalisi dettagliata delle distribuzioni energetica e temporale del burst. Oltre allastrofisica neutrinica, con lesperimento LVD si possono compiere ricerche in fisica della radiazione cosmica e di particelle elementari ad altissime energie.РезюмеВ данной работе описывается зксперимент LVD (Large Volume Detector), который будет проводиться в лаборатории Гран Cacco. LVD является естественным продолжением эксперимента LSD (Liquid Scintillation Detector) в лаборатории Монблан. LVD (площадь (31×13) м2, высота 12 м) содержит 1800 тонн жидкого сцинтиллятора и включает в себя систему стримерных детекторов, размещенных на 5 уровнях. Последние используются для реконструкции треков заряженных частиц. Как и любой длительный эксперимент в подземных условиях, когда статистика событий невелика, LVD имеет многоцелевое назначение. Научные программы, однако, будут обладать различным приоритетом. Основное внимание будет уделяться нейтринной астрономии, и в первую очередь— детектированию нейтрино от коллапсирующих звезд. Кроме того, будут проводиться исследования по регистрации нейтрино высоких энергий и солнечных нейтрино. Поскольку ожидаемое количество взаимодействий в случае прихода потока нейтрино от коллапса очень велико, порядка 900, LVD будет настоящей нейтринной обсерваторией, способной, в отличие от ведущихся сейчас экспериментов, детально исследовать энергетическое временное распределения для вспышки нейтринного излучения. В дополнение к нейтринной астрофизике, имеются очень хорошие перспективы и для исследований в области космических лучей и физики элементарных частиц высоких энергий.