Intermediate Sensors
EPIC Intermediate-Period Sensors:
Features:
The low-period corner is 30 seconds for the 3 Guralps and is 40 seconds for the Nanometrics sensor. All are 3-component feedback sensors. The CMG40T and Trillium40 masses do not lock. One should still ship and handle them with care so as not to damage them. The CMG3-ESP has masses that require manual locking and unlocking. For information on the CMG40T with corner-frequencies of 1-sec, click here.
Historically, the ESP's were among the first feedback sensors purchased for the EPIC program, along with STS-2's. For that reason, the ESP's have been 'categorized' as broadband sensors when broadband stations are scheduled for EPIC experiments. The ESP's are an ever-decreasing percentage of the EPIC broadband pool and we attempt to assign them as evenly as possible, roughly 10% of the sensors for a broadband experiment from 2006 onward, and that number should decrease further after 2009.
The noise characteristics of the three intermediate sensors differ. The good ESP's are almost as quiet as a Guralp CMG3T at periods from 0.005 - 0.05 Hz. As they age, however, there are fewer and fewer good ESP's. Trillium40 sensors are noisy below about 10 seconds, but not nearly as noisy as CMG40T's.
