This particular application calls for the thinnest mica of 1.5-2.0 mg/cm2 areal density thickness ,because the efficacy of the geiser counter is supposed to be directly proportionate to thicknessof mica sheets used.

Muscovite mica crystals have alternating layers of aluminosilicate and potassium ions.The one-atom thick layersd of potassium ions are very easy to split apart into thinnest film,while aluminosilicate layers are tightly bonded together.As a result, extremely thin sheets of muscovite mica can easily separated,yet these thin sheets are flexible and though.Besides,muscovite mica have excellent dielectric,thermal,mechanical and chemical properties and can withstand rigorous shock and vibration testing.
Muskovite mica being a natural inorganic mineral,it can also absorb ionizing radiation effects.It aso has the advantage of fairly low specific gravity,besides it does not have an abrasive effect on machinery.As such,muscovite mica is the obvios choice for dicerning user of GM tubes which are supposed to exhibit superior performance,reliability and long- term stabiliyt to meet the wide range of environments varying from laboratory to severe military and industrial conditions.