How Many IVUs Can We Install without Sacrificing 16-mA Operation?

Let’s define the vertical impedance of an 8-mm gap chamber due to geometric variation as one unit of impedance with the symbol zu. Since the resistive wall impedance of an 8mm gap chamber is 0.3 zu [2], the total impedance of an 8-mm gap chamber is 1.3 zu. The geometric impedance of a 5-mm gap chamber is 3.09 zu, which we obtained using the known scaling in Eq. (1) derived in [1]. Including 1.23 zu (0.3 zu of 8-mm gap scaled by 1/g) for resistive wall, the total impedance of a 5-mm gap chamber will then be 4.32 zu. Thus, the nominal configuration of 1×29, which consists of one 5-mm and 29 8-mm gap chambers, will have a total ID chamber impedance of 42.02 zu. This is the reference impedance that will be used as a normalization factor for different configurations.