Making spin traps Firing a bullet into a punchbag can make the latter locally hot, but it will not move very much. The lightweight bullet may have high kinetic energy (0.5MV2), but only low momentum (MV) and low angular momentum (MVr), even if it hits the punchbag well offcentre (hereM is the mass of the bullet, V is its velocity, and r is the impact parameter). It is the same with nuclei. Firing a proton into 180 72Hf108 with enough energy to overcome the electrostatic repulsion makes 181 73Ta108 at relatively low angular momentum, but at sufficiently high excitation energy to `boil off ' two neutrons to become 179 73Ta106. g-ray emissions follow, corresponding to transitions between quantum states, in a sequence that takes 179Ta down to its ground state, but only through states with low spin. Fusion reactions. Heavier projectiles are needed to make high-spin isomers, with fusion-evaporation reactions of the type illustrated in Fig. 3a. The record for a K-trap has been set12 by colliding 48Ca into 130Te. After fusion, which forms 178Hf, the excitation energy favours the emission of four neutrons which would lead to states in 174Hf . Occasionally only three neutrons are `evaporated', resulting in a rapidly spinning 175Hf nucleus, which sometimes is trapped in an isomeric state with (57/2) ~ of spin at an excitation energy of 7.5MeV. However, the low probability of the formation path makes difficult the study of 175Hf at high spin with this reaction. (As a result, the 7.5-MeV isomer has yet to have its half-life measured.) To do better, an initial beam or target with more neutrons is needed, but for calcium and tellurium these heavier isotopes are all unstable, with half-lives shorter than days, so they are unavailable for beams and targets at present. Developments in radioactive-beam technology13 should soon remedy this. The heaviest isotope of hafnium that presently can be studied with fusion-evaporation reactions is 178 72Hf106, made by colliding 4He into 176Yb, and involving the evaporation of two neutrons. This reaction brings in, at the most, 16 units of spin, just enough14 to make the K ˆ 16 trap at 2.4MeV, which has a half-life of 31 years.
Crude Inventories Surge To Record High As Energy Demand Collapses Submitted by Tyler Durden on 05/01/2013 11:38 -0400 Crude None Railcar Loadings Reality A month ago we highlighted the somewhat stunning reality of the real economy via the EIA's detailed energy supply and demand data. The key takeaway was that we hoped this did not represent the true state of the economy since the data was so dismal. Fast forward to today and the DOE just released a much higher than expected build in crude inventories that took the stuffed-channel of oil products to all-time highs. The 395.3 million barrels is higher than the previous record in July 1990. There appears to be a number of factors at play - none of which are positive. There is a surge in supply due to the incessant harvesting of shale oil (which could have its own problems as we noted here ). Second, we suspect there is a degree of 'channel-stuffing' occurring - if we pump it, they will buy - as producers and transporters are desperate to keep active and show incremental business (despite fading railcar loadings). But perhaps most important, as EIA data has shown , there has been a collapse in end demand for crude products not seen since the 1990s. Today's surge in inventories appears to confirm demand remains subdued at best. Chart: Bloomberg
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