Hadron shower decomposition in a highly granular calorimeter
The spatial development of showers induced by positive hadrons with momenta 10-80 GeV in the highly granular CALICE scintillator-steel analogue hadronic calorimeter is analysed. The parametrisation of both longitudinal and radial shower profiles with the two- component functions are fit to the test beam data and simulations using the physics lists QGSP_BERT and FTFP_BERT from GEANT4 version 9.6 patch 01. The shower parameters, describing the longitudinal tail and radial halo, are in good agreement between data and simulations and are similar for pions and protons. For the longitudinal development, the most significant difference between data and simulations is in the relative containment of the separated components. For the radial development, the core slope parameter is underestimated by simulations. The physics list FTFP_BERT gives a very good description of proton showers in the studied energy range and gives better predictions of the pion shower development than QGSP_BERT.
Beam test of a small MICROMEGAS DHCAL prototype
A sampling hadronic calorimeter with gaps instrumented with thin MICROMEGAS chambers of small pad size and single bit readout is a candidate for an experiment at a future linear collider. Several MICROMEGAS chambers with 1 cm2 anode pads were fabricated using the Bulk technology. Some prototypes equipped with analog readout GASSIPLEX chips were developed for characterisation at the CERN/PS facility. A stack of four chambers and stainless steal absorber plates was used to assess the behaviour of MICROMEGAS in 2 GeV electron showers. Longitudinal and transverse shower profile are shown. The Bulk fabrication process was adapted to laminate a mesh on anode PCBs with front-end chips connected on the backside. It is well suited for the construction of a 1 m3 DHCAL-MICROMEGAS prototype as large and thin chambers can be made. Such chambers with digital readout chips (HARDROC or DIRAC) were fabricated and tested in a beam. First results are presented.
Urea removal strategies for dialysate regeneration in a wearable artificial kidney.
The availability of a wearable artificial kidney (WAK) that provides dialysis outside the hospital would be an important advancement for dialysis patients. The concept of a WAK is based on regeneration of a small volume of dialysate in a closed-loop. Removal of urea, the primary waste product of nitrogen metabolism, is the major challenge for the realization of a WAK since it is a molecule with low reactivity that is difficult to adsorb while it is the waste solute with the highest daily molar production. Currently, no efficient urea removal technology is available that allows for miniaturization of the WAK to a size and weight that is acceptable for patients to carry. Several urea removal strategies have been explored, including enzymatic hydrolysis by urease, electro-oxidation and sorbent systems. However, thus far, these methods have toxic side effects, limited removal capacity or slow removal kinetics. This review discusses different urea removal strategies for application in a wearable dialysis device, from both a chemical and a medical perspective.