arXiv subjects

Frederic Bouquet

Publications and source records attributed to Frederic Bouquet.

4 recordsLinked to original sources

arXiv2021

61 ways to measure the height of a building: an introduction to experimental practices

We created an introductory physics activity for undergrad students consisting in measuring by different methods the same physical quantity. It allows to confront students with questions of uncertainty, precision, and model versus theory. The aim was to measure the height of a building using only a smartphone and everyday low-cost equipment. We designed 61 methods to do so and tested most of them. These methods can be implemented in various pedagogical scenarios, engaging students into a concrete task, outside of the lab, easily set up at almost zero cost.

physics.ed-ph↗

arXiv2005

Modulated-bath AC calorimetry using modified commercial Peltier-elements

We developed a new type of AC microcalorimeter based on a modulated-bath technique for measuring the specific heat of small microgram samples in the temperature range from 30-300 K, and tested it in magnetic fields up to 14 T. The device is built from a modified commercial Peltier element. The temperature of its top plate can be modulated periodically by Peltier effect, so that the oscillation is symmetrical about the temperature of the main bath. This avoids the problem of DC offsets which plagues conventional AC calorimeters. The sample is attached to a thin thermocouple cross, acting as a weak thermal link to a platform. The absence of a heater reduces the background heat capacity ('addenda') to a minimum. As an illustrative example of the performance of our device, the specific heat in fields up to 14 T of a small single crystal of the high-temperature superconductor Bi2.12Sr1.71Ca1.22Cu1.95Oy has been determined.

cond-mat.other↗

arXiv2003

Specific heat of MgB_2 after irradiation

We studied the effect of disorder on the superconducting properties of polycrystalline MgB_2 by specific-heat measurements. In the pristine state, these measurements give a bulk confirmation of the presence of two superconducting gaps with 2 Delta 0 / k_B T_c = 1.3 and 3.9 with nearly equal weights. The scattering introduced by irradiation suppresses T_c and tends to average the two gaps although less than predicted by theory. We also found that by a suitable irradiation process by fast neutrons, a substantial bulk increase of dH_{c2}/dT at T_c can be obtained without sacrificing more than a few degrees in T_c. The upper critical field of the sample after irradiation exceeds 28 T at T goes to 0 K.

cond-mat.supr-con↗

arXiv2001

Specific heat of the 38-K superconductor MgB_2 in the normal and superconducting state: bulk evidence for a double gap

The specific heat of two polycrystalline samples of MgB_2 is presented and analyzed (2 - 300 K, 0 - 16 T), together with magnetic properties. The main characteristics are a low density of states at the Fermi level, high phonon frequencies, and an anomalous temperature- and field- dependence of the specific heat at T < T_c. A two-gap model with a gap ratio of 3:1 fits the specific heat in zero field. The smaller gap is washed out by a field of 0.5 T.

cond-mat.supr-con↗