The lateral distribution of energetic shower muons

Summary The customary assumption of a unique structure function of the formf(r)∞r ^−αexp[−r/R ₀] with parameters independent of the shower size and the nature of the primary is tested against evidence on the multiplicity distribution of shower muons. The experimental data were obtained with an array of three spark chamber telescopes installed at the Mt. Cappuccini underground station, Torino, at depths of about 40 to 60 hg/cm². They pertain to events with mean shower sizes between about 10⁵ and a few 10⁷ electrons. It is shown that the results are incompatible with this assumption, whatever values are assigned to the exponent α and to the characteristic radiusR ₀ of the structure function. A modified representation allowing for a variation ofR ₀ with the shower size and with the massA of the primary is suggested. The resulting distribution is in reasonable agreement both with thorough Monte Carlo evaluations for proton and iron primaries and with direct experimental observations of other authors.

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Riassunto L'ipotesi usuale di una funzione di struttura unica della formaf(r)∞r ^−αexp[−r/R ₀] con parametri indipendenti dalle dimensioni dello sciame e dalla natura dei primari è provata rispetto alle prove sperimentali sulla distribuzione di molteplicità dei muoni dello sciame. I dati sperimentali sono stati ottenuti con un sistema di tre telescopi con camere a scintille istallati nella stazione sotterranea del Monte dei Capuccini, Torino, a profondità da 40 a 60 hg/cm². Essi riguardano eventi con grandezze medie di sciami tra circa 10⁵ e pochi 10⁷ elettroni. Si mostra che i risultati non sono compatibili con questa ipotesi, qualsiasi valore sia assegnato all'esponente α e al raggio caratteristicoR ₀ della funzione di struttura. Si suggerisce una rappresentazione modificata che consente una variazione diR ₀ con la grandezza dello sciame e con la massaA dei primari. La distribuzione risultante è in ragionevole accordo sia con tutte le valutazioni di Montecarlo per primari di protoni e di ferro e con osservazioni sperimentali dirette di altri autori.

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Резюме Исследуется обычное предположение о единственной структурной функции видаf(r)∼r ^−αexp[−r/R ₀], с параметрами, не зависяцими от размеров ливня и природы первичной частицы, на основе данных о распределении множественности мюонов в ливне. Зкспериментальные данные получены с помошью системы трех телескпов искровых камеп, установленных на подземной стандии Капучини в Турине, на глубинах от 40 до 60 гг/см². Полученные данные относятся к событиям со средними размерами ливня от 10⁵ до 10⁷ злектронов. Показывается, что полученные результаты являются несовместимыми с зтим предположением, какие бы значения зкспоненте α и характерному радиусуR ₀ структурной функции не были бы приписаны. Предлагается модифицированное представление, учитывающее изменение велиьиныR ₀ с размером ливия и с массойA первичной частицы. Полученное распределение хорошо согласуется и с оценками по Монте-Карло для первичных протонов и ядер железа и с непосредственными экспериментальными результатами других авторов.

     

Ma?analytische Bestimmung von Barium mit Ammonium-Cer(IV)-nitrat

Zusammenfassung Barium gibt mit Oxaldihydroxamat quantitativ einen weißen Niederschlag, der gut filtrierbar ist. Die Oxaldihydroxamsäure läßt sich bei Gegenwart von Sulfamidsäure mit (NH₄)₂Ce(NO₃)₆-Titerlösung und Nitroferroin als Indicator maßanalytisch bestimmen. Versuche, das Barium über das Oxalat cerimetrisch zu bestimmen, verliefen negativ. Zur Bestimmung des Bariums wird mit Hydroxamat gefällt und dieses nach Lösen des Niederschlages cerimetrisch bestimmt.

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Summary Barium may be precipitate quantitatively with oxaldihydroxamate. The white, crystalline precipitate can be filtered easily. Oxaldihydroxamic acid may be titrated in presence of sulphamic acid with a (NH₄)₂Ce(NO₃)₆ standard solution using nitroferron as indicator. The cerimetric determination of barium via the oxalate has been tried without success. In the proposed method barium is precipitated with hydroxamate and the latter is determined by cerimetry after dissolution of the precipitate.

     

An intermolecular force field for chlorinated benzene crystals

Intermolecular potential parameters corresponding to atom—atom interactions of the Buckingham form are refined on the basis of static and dynamic properties of some chlorinated benzene crystals. The model reproduces well the observed properties, including k ≠ 0 vibrations.     

Thiolutidinsäure-N,N′-dimethylamid als empfindliches Eisenreagens

Zusammenfassung Thiolutidinsäure-N,N-dimethylamid (TLSMA) bildet bei pH 14 ein violett gefärbtes Eisen(II)chelat mit hohem molarem Extinktionskoeffizienten. Das Reagens ist sehr empfindlich und hat in saurem Milieu reduzierende Eigenschaften. pH-Abhängigkeit, zeitlicher Verlauf der Komplexbildung und die Zusammensetzung des Chelats wurden untersucht. Ein Verfahren zur spektralphotometrischen Bestimmung von Eisenspuren (0,04–4g/ml) wurde beschrieben.

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Thiolutidinic acid-N,N-dimethylamide as sensitive iron reagent

Summary At pH 14, thiolutidinic acid-N,N-dimethylamide yields a violet iron(II)-chelate with a high molar extinction coefficient. The reagent is very sensitive and has reducing properties in acid milieu. Its pH-dependence, the relation of time to the complex formation and the composition of the chelate were investigated. A procedure for the spectrophotometric determination of traces of iron (0.04 to 4g/ml) is decribed.

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Herrn Prof. Dr. Erich Ziegler zum 60. Geburtstag gewidmet.     

Killing Symmetries of Generalized Minkowski Spaces, 3: Spacetime Translations in Four Dimensions

In this paper, we continue the study of the Killing symmetries of a N-dimensional generalized Minkowski space, i.e., a space endowed with a (in general non-diagonal) metric tensor, whose coefficients do depend on a set of non-metrical coordinates. We discuss here the translations in such spaces, by confining ourselves (without loss of generality) to the four-dimensional case. In particular, the results obtained are specialized to the case of a deformed Minkowski space (i.e. a pseudoeuclidean space with metric coefficients depending on energy).     

How many hydrogen atoms can be bound to a metal? Predicted MH12 species

Quantum chemical calculations predict the existence of new molecular species with general formula MH12, where M is a group 6 atom. The previous MHn species had n values up to 9. The new systems with n = 12 would be a new record for metal hydrides.     

Classifying Genus Two 3-Manifolds up to 34 Tetrahedra

In this paper, we present a catalogue of all genus two 3-manifolds admitting a contracted triangulation with at most 34 simplexes. Then we give a complete classification of the above manifolds. Mathematics Subject Classifications (2000) 57M05, 57N10, 57M15.Work performed under the auspicies of the G.N.S.A.G.A. of the C.N.R. (National Research Council of Italy) and financially supported by M.I.U.R. of Italy (project Strutture geometriche delle varietà reali e complesse).     

A 3.5-mW continuous-wave difference-frequency source around 3 μm for sub-Doppler molecular spectroscopy

We report the development of a mid-infrared tunable coherent radiation source, based on difference-frequency generation (DFG). The signal and pump beams coming from two cw rare-earth-doped amplifiers are mixed into a periodically-poled LiNbO₃ crystal to produce radiation in the 2.9–3.5 m spectral range. For the first time to our knowledge, an output power of several mW has been achieved. We show that such a power can be exploited for high-resolution investigation of molecular absorption spectra. Saturation Lamb-dips have been observed for a number of ro-vibrational transitions belonging to the CH_{4 3} fundamental band. PACS 42.65Ky; 33.20 Ea     

Predicted group 4 tetra-azides M(N3)(4) (M = Ti-Hf,Th): the first examples of linear M-NNN coordination

Quantum chemical calculations suggest that group 4 tetra-azides M(N(3))(4), where M = Ti, Zr, Hf, and Th, are stable species. They present a unique structural feature; namely, the M-N-N-N fragments are linear. These species are energetically more stable than the corresponding isomers with general formula eta(5)-N(5) -M-eta(7)-N(7), and the Th species, Th(N(3))(4), is the most stable of all. Possible mixed nitride azides NMN(3) were also investigated.