: Construction of the first stage of the Pierre Auger Observatory has begun. The aim of the Observatory is to collect unprecedented information about cosmic rays above 10(18) eV. The first phase of the project, the construction and operation of a prototype system, known as the engineering array, has now been completed. It has allowed all of the sub-systems that will be used in the full instrument to be tested under field conditions. In this paper, the properties and performance of these sub-systems are described and their success illustrated with descriptions of some of the events recorded thus far. (C) 2003 Elsevier B.V

a b s t r a c tThe Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions.

We report electron-paramagnetic resonance ͑EPR͒ studies at ϳ9.5 GHz ͑X band͒ and ϳ34 GHz ͑Q band͒ of powder and single-crystal samples of the compound Cu 2 ͓TzTs͔ 4 ͓N-thiazol-2-yl-toluenesulfonamidatecopper͑II͔͒, C 40 H 36 Cu 2 N 8 O 8 S 8 , having copper͑II͒ ions in dinuclear units. Our data allow determining an antiferromagnetic interaction J 0 = ͑−113Ϯ 1͒ cm −1 ͑H ex =−J 0 S 1 • S 2 ͒ between Cu͑II͒ ions in the dinuclear unit and the anisotropic contributions to the spin-spin coupling matrix D ͑H ani = S 1 • D • S 2 ͒, a traceless symmetric matrix with principal values D / 4=͑0.198Ϯ 0.003͒ cm −1 and E / 4=͑0.001Ϯ 0.003͒ cm −1 arising from magnetic dipole-dipole and anisotropic exchange couplings within the units. In addition, the singlecrystal EPR measurements allow detecting and estimating very weak exchange couplings between neighbor dinuclear units, with an estimated magnitude ͉JЈ͉ = ͑0.060Ϯ 0.015͒ cm −1 . The interactions between a dinuclear unit and the "environment" of similar units in the structure of the compound produce a spin dynamics that averages out the intradinuclear dipolar interactions. This coupling with the environment leads to decoherence, a quantum phase transition that collapses the dipolar interaction when the isotropic exchange coupling with neighbor dinuclear units equals the magnitude of the intradinuclear dipolar coupling. Our EPR experiments provide a new procedure to follow the classical exchange-narrowing process as a shift and collapse of the line structure ͑not only as a change of the resonance width͒, which is described with general ͑but otherwise simple͒ theories of magnetic resonance. Using complementary procedures, our EPR measurements in powder and single-crystal samples allow measuring simultaneously three types of interactions differing by more than three orders of magnitude ͑between 113 cm −1 and 0.060 cm −1 ͒.

Hydride complexes IrHCl(2)(PiPr(3))P(2) (1) and IrHCl(2)P(3) (2) [P = P(OEt)(3) and PPh(OEt)(2)] were prepared by allowing IrHCl(2)(PiPr(3))(2) to react with phosphite in refluxing benzene or toluene. Treatment of IrHCl(2)P(3), first with HBF(4).Et(2)O and then with an excess of ArCH(2)N(3), afforded benzyl azide complexes [IrCl(2)(eta(1)-N(3)CH(2)Ar)P(3)]BPh(4) (3, 4) [Ar = C(6)H(5), 4-CH(3)C(6)H(4); P = P(OEt)(3), PPh(OEt)(2)]. Azide complexes reacted in CH(2)Cl(2) solution, leading to the imine derivative [IrCl(2){eta(1)-NH=C(H)C(6)H(5)}P(3)]BPh(4) (5). The complexes were characterized by spectroscopy and X-ray crystal structure determination of [IrCl(2)(eta(1)-N(3)CH(2)C(6)H(5)){P(OEt)(3)}(3)]BPh(4) (3a) and [IrCl(2){eta(1)-NH=C(H)C(6)H(5)}{P(OEt)(3)}(3)]BPh(4) (5a). Both solid-state structure and (15)N NMR data indicate that the azide is coordinated through the substituted Ngamma [Ir]-Ngamma(CH(2)Ar)NNalpha nitrogen atom.

The trichlorostannyl complexes M(SnCl3)(CO)nP5-n (1−3: M = Mn, Re; P = PPh(OEt)2 (a), P(OEt)3 (b); n = 2, 3) were prepared by allowing chloro MCl(CO)nP5-n compounds to react with an excess of SnCl2·2H2O. Treatment of compounds 1−3 with NaBH4 in ethanol yielded the tin polyhydride derivatives M(SnH3)(CO)nP5-n (4−6). Treatment of 1−3 with MgBrMe gave the trimethylstannyl complexes M(SnMe3)(CO)nP5-n (7−9), and the reaction of 1−3 with MgBr(C≡CH) yielded the trialkynylstannyl derivatives M[Sn(C≡CH)3](CO)nP5-n (10, 11). The alkynylstannyl complexes M[Sn(C≡CR)3](CO)nP5-n (12−14: R = p-tolyl) were also prepared by allowing M(SnCl3)(CO)nP5-n compounds to react with Li+[C≡CR]- in thf. The complexes were characterized by spectroscopy and by X-ray crystal structure determinations of 4a, 6b, and 9b. Reaction of the tin trihydride complexes Re(SnH3)(CO)2P3 (6) with CO2 (1 atm) led to the binuclear OH-bridging bis(formate) derivatives [Re{Sn[OC(H)=O]2(μ-OH)}(CO)2P3]2 (15). A reaction path for the formation of 15, involving the tin hydride bis(formate) intermediate Re[SnH{OC(H)=O}2](CO)2P3, is discussed. The X-ray crystal structure of 15b is reported

The first example of evolution of an iridanaphthalene into an indanone through an intermediate indenyl is reported, serving as a good example of starting material to obtain indanones. Two new iridanaphthalenes are obtained by intramolecular C−H activation of a phenyl ring of a carbene ligand in [IrCp*{C(OMe)CHCPh 2 }(L)]PF 6 (L = PPh 2 Me, PMe 3 ) complexes. It is demonstrated that these iridanaphthalene complexes can undergo a thermal reaction to give indenyl complexes and 3-phenylindanone.M etallacyclic aromatic compounds incorporating transition metals are a subject of great interest, since they display a behavior that includes properties from both aromatic organic and organometallic compounds. Although many metallabenzenes of osmium, iridium, platinum, and ruthenium are known, to the best of our knowledge only two metallanaphthalenes have been reported, one with osmium 1 and another with iridium. 2 The importance of this type of metal-organic functionality is emphasized by the fact that metal cyclopentadienyls can be formed from transitory metallabenzenes. 3 Analogously, an osmanaphthalene has been proposed as intermediate leading to an indenyl complex. 4 Recently, we have reported that the new (methoxy)-alkenylcarbeneiridium complex [IrCp*Cl{C(OMe)CH CPh 2 }(PPh 2 Me)]PF 6 (1a) reacts with amines to undergo the unexpected cleavage of the O−CH 3 bond instead of the usual aminolysis. 5 This peculiar behavior has prompted us to further explore the reactivity of these types of compounds. Here, we report that treatment of [IrCp*Cl{C(OMe)CHCPh 2 }-(L)]PF 6 (L = PPh 2 Me (1a), PMe 3 (1b)) with AgPF 6 gives high yields of the iridanaphthalene complexes [IrCp*{C(OMe)-CHC(o-C 6 H 4 )(Ph)}(L)]PF 6 (L = PPh 2 Me (2a), PMe 3 (2b)) through an intramolecular C−H activation of one of the phenyl rings of the carbene ligand (eq 1).The structures of both iridanaphthalene complexes have been confirmed by single-crystal X-ray diffraction (see the Supporting Information). Figure 1 shows the complex cation 2a. The iridium atom becomes part of a metallanaphthalene moiety and the metal coordination sphere is completed with a pentamethylcyclopentadienyl (Cp*) and a phosphane ligand.The NMR spectra support the solid-state structures of 2a,b (see the Supporting Information).Remarkably, the iridanaphthalene moiety is not stable and refluxing 2 in 1,2-dichloroethane or toluene for 24 h gives 3-phenylindanone (4) (eq 2). The same transformation occurs also at longer reaction times in dichloromethane at 35°C (eq 2).

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Two new uranyl(vi) Schiff base complexes were synthesized and characterized by physicochemical and spectroscopic methods. The antimicrobial activities of these complexes were also investigated against microorganisms.