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The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km. The measurement is based on data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies.An arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (6.5 ± 7.4 (stat.) +8.3 −8.0 (sys.)) ns was measured corresponding to a relative difference of the muon neutrino velocity with respect to the speed of light (v − c)/c = (2.7 ± 3.1 (stat.) +3.4 −3.3 (sys.)) × 10 −6 . The above result, obtained by comparing the time distributions of neutrino interactions and of protons hitting the CNGS target in 10.5 µs long extractions, was confirmed by a test performed at the end of 2011 using a short bunch beam allowing to measure the neutrino time of flight at the single interaction level.

OCS was photodissociated near 217 and 230 nm, and the resulting CO was probed by 2 + 1 resonant multiphoton ionization (REMPI) using the B ' F , C'X+ -X'Z+ transitions. The CO+ was detected by the ion imaging technique of Chandler and Houston. The nascent CO was found only in the v = 0 state, and its rotational state population distribution was bimodal. It is remarkable that this CO rotational distribution has no tail extending to states of lower J. / 3 values rise monotonically with J. Recent potential energy surface calculations by Rokutan et al. provide reasonable explanations for the results: (1) dissociation can take place from near degenerate A" and A' states, each of which generates a different CO product distribution; (2) a molecule excited by the initial absorption to an A' state can cross over in linear geometry at two different C-S distances to dissociating states. IntroductionThe dynamics of photodissociation can be most simply studied with triatomic molecules because their potential energies depend on only three coordinates. OCS is a particularly interesting molecule to investigate because there is an additional simplification in that the C-0 bond length seems to be only a spectator in the dissociation process. The C-0 bond length is 1.157 8, in OCS and 1.128 8, in CO. Moreover on photodissociating OCS the CO is liberated only in the v = 0 state. Strong forces act during the dissociation event but evidently not on the C-0 bond length, which therefore can be frozen without affecting the physics. The photodissociation of OCS has been investigated by Paul Houston's group in the first very weak absorption band (222, 235, and 248 n m ) ' s 2 and in an allowed band at 157 nm. At 222 nm there is approximately a 6% yield of S(3P), but the major channel is to CO(v=O) and S(1D).2 The CO is strongly rotationally excited. At 222 nm the distribution of J-state populations has two peaks, the major one at J = 56 and a secondary weaker maximum at J = 67. At 235 and 248 nm the secondary peak is no longer seen and the major peak has decreased to lower Ss, that is, J = 45 (235 nm) and J = 31 (248 nm). The high rotational excitation implies that a strong torque is exerted on the CO fragment as it separates. In other words, when the OCS molecule is excited in its first absorption band from its linear X'X+ ground state, the upper state is bent. This result is entirely in accord with Walsh's rules which predict that for a triatomic, the energy of the ninth valence molecular orbital decreases as the molecule is bent.4 The opposite is true of the eighth molecular orbital. Therefore a low-energy excitation in a 16 valence electron triatomic is invariably to a bent upper state. OCS photodissociation is important as a paradigm of this process.The photofragment velocity anisotropy parameter measured by Sivakumar et al. was ,8 = 1.9 f 0.1 for the higher J @ Abstract published in Aabance ACS Abstracts, October 15, 1995. 0022-365419512099-16307$09.00/0 maximum and ,8 = 0 for the lower J maximum. This quite unprecedented result brin...

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