"The trauma of competition": the entry of Air Products Inc. into the industrial gases business in Britain and continental Europe 1947-1970

The British Oxygen Company (BOC) had a virtual monopoly on the supply of industrial gases (e.g. oxygen and acetylene) on the British market through the 1950s, when it was finally challenged by an American-based company, Air Products. Air Products Limited (APL) was able to undercut BOCs position, overcoming high barriers to entry to gain significant market share in this sector, which shares some features of network industries. Factors in this success included conditions imposed by the Board of Trade, APL’s innovations, BOC’s slow response, and favourable market conditions. APL’s success had implications for the internationalisation of the industrial gases industry

A levitated droplet of superfluid He-3-B entirely surrounded by He-3-A.

From our long experience of using profiled magnetic fields to stabilize and manipulate the A-B phase boundary in superfluid He-3, we have constructed a cell in which we can create and move a droplet of B phase, levitated within A phase away from any walls at T similar to 0.15 T-c. Uniquely, the A and B condensates are coherent across the A-B interface and at such low temperatures the superfluid is essentially pure, providing the most ordered phase boundary to which we have laboratory access. We configure the field so that within a bulk volume of superfluid, a region of high field (stabilizing the A phase) completely surrounds a region of lower field (stabilizing the B phase). Our preliminary measurements are at zero pressure and temperatures below 0.3T(c) where the first-order transition from B to A phase is at 340 mT. We observe the formation of the droplet as we ramp the field, and we also study the transport of thermal excitations out of the droplet. Future plans include measurements at higher pressures where the A phase can be stabilized in low magnetic field at temperatures close to T-c. Upon cooling into the B phase we should then be able to make the first studies of nucleation uninfluenced by the presence of container walls

Magnetic distortion of the B-like phase of superfluid He-3 confined in aerogel.

We present measurements of the response of the B-like phase of superfluid He-3 in aerogel to an applied flow. The measurements are made using a cylindrical piece of 98% silica aerogel attached to a vibrating wire resonator. The resonator is immersed in superfluid He-3 at 16 bar pressure and at low temperatures. A variable magnetic field is applied such that the aerogel-confined superfluid may exist in the A-like or B-like phase, while the surrounding fluid is always in the bulk B-phase. The resonator response reveals a velocity dependence of the inferred aerogel-confined superfluid fraction. We discuss measurements of the temperature and magnetic field dependence of the response in the B-like phase. We find a significant field dependence indicating a strong magnetic distortion of the B-like phase order parameter

Plastic properties of solid 4He probed by a moving wire:viscoelastic and stochastic behavior under high stress

We present measurements of a thin wire moving through solid 4He. Measurements were made over a wide temperature range at pressures close to the melting curve. We describe the new experimental technique and present preliminary measurements at relatively high driving forces (stresses) and velocities (strain rates). The wire moves by plastic deformation of the surrounding solid facilitated by quantum tunneling of vacancies and the motion of defects. In the bcc phase we observe very pronounced viscoelastic effects with relaxation times spanning several orders of magnitude. In the hcp phase we observe stochastic step-like motion of the wire. During the step, the wire can move at extremely high velocities. On cooling, the wire ceases to move at a temperature of around 1 K. We are unable to detect any motion at lower temperatures, down to below 10 mK

Response of a mechanical oscillator in solid 4He

We present the first measurements of the response of a mechanical oscillator in solid 4He. We use a lithium niobate tuning fork operating in its fundamental resonance mode at a frequency of around 30 kHz. Measurements in solid 4He were performed close to the melting pressure. The tuning fork resonance shows substantial frequency shifts on cooling from around 1.5 K to below 10 mK. The response shows an abrupt change at the bcc-hcp transition. At low temperatures, below around 100 mK, the resonance splits into several overlapping resonances

Relic topological defects from brane annihilation simulated in superfluid He-3.

Although it is widely accepted that to resolve the 'horizon' problem the early Universe must have undergone a sudden expansion (cosmic inflation), what mechanism drove this process is less clear. In the braneworld scenario, it is suggested that inflationary epochs may have been initiated and terminated by brane collisions and annihilations. Branes are objects of lower dimensionality embedded in a higher-dimensional matrix. For example, we may live on a three-dimensional brane embedded in a four-dimensional matrix. However, such structures are so far removed from everyday reality that bringing physical insight to bear is difficult. Here we report laboratory experiments where we simulate brane annihilation using the closest brane analogue to which we have access, the coherent phase boundary between the two phases of superfluid He-3. When two branes collide or annihilate, topological defects may be created, whose influence may still be detectable today. By creating a brane-antibrane pair in superfluid He-3 and subsequently annihilating it, we can detect that defects are indeed created in the superfluid texture (the superfluid analogue of spacetime), thus confirming that the concept of defect formation after brane annihilation in the early Universe can be reproduced in analogous systems in the laboratory

The AB interface in superfluid He-3 as a simulated cosmological brane.

We present measurements of the transport of superfluid He-3 quasiparticle excitations in the ballistic limit at temperatures well below T-c , and an interpretation of unexpected results as an experimental simulation of cosmological processes. Using a variable magnetic field profile we stabilize a layer of A phase across a cylinder of B phase, creating both an AB and a BA interface. These highly ordered interfaces may provide an ideal laboratory analogy for the branes and anti-branes of current cosmology. It has been suggested that brane interaction and annihilation are involved in inflation in the early Universe and leave behind topological defects such as cosmic strings. In our experiments we have annihilated our AB/BA branes by ramping down the magnetic field to remove the A phase layer. We then find that the quasiparticles face an extra impedance owing to defects left behind in the B phase texture. This is the first definitive observation of such a phenomenon