A multi-purpose efficient charge particle detector that by switching bias voltages measures either secondary ions, or secondary electrons from a sample, or secondary electrons that originate from back scattered electrons, is described. An average temperaturegradient temperature calculating means calculates the average temperatures of the temperatures measured by the temperature sensors and the gradient temperatures based on the measured temperatures. Quantitative real-time RT-PCR analysis of PKS-like sequences mined from isolated root hairs revealed that two sequences, designated ARS1 and ARS2, were preferentially expressed.