Crates and Modules

The various crates used to hold the PrimEx electronics will be fixed in 4 electronics racks which are of the same style as those already in use in Hall-B. A diagram illustrating the layout of these crates is shown in figure 1. A total of 30 LRS1881M ADC modules will be required. The space required for each delay cable bundle prevents any ADC modules from being placed in adjacent slots. Thus, 3 fastbus crates are needed to hold all 30 ADC modules and 1 LRS1877 TDC module.

Figure 1: Map of PrimEx Electronics Racks. This is not exactly to scale, but it is reasonably close.

The trigger (described in section 1.2.1) is based on UVA120A and UVA125A NIM modules. The design of these modules was modified specifically for primex based on the signal size and timing requirements expected. A total of 56 UVA120A modules (36 input, 2 output linear fan-ins) and 4 UVA125A (quad 9 input linear fan-in with discriminator) modules are needed. The power requirements of the UVA120A units are quite modest while those of the UVA125A are somewhat more demanding. UVA has provided primex with 6 high powered NIM crates for use with these modules.