During 1999, EXPLORER underwent a complete overhaul of its read-out chain. The detector has been equipped with a new "rosette" capacitive transducer (with a gap of about 10 µm) and a commercial d.c. SQUID by Quantum Design.
In march 2000 the experiment started to operate in a new configuration.
This led to a remarkable improvement in sensitivity and stability: a detector noise temperature of about 2 mK and a bandwidth of about 10 Hz, one order of magnitude larger than that of the other operating resonant detectors, have been obtained.

The detector duty cycle is about 80% due to cryogenic operations and maintenance.

The picture above shows the experimental strain sensitivity of EXPLORER in 2001 (input noise spectral amplitude in units of m Hz^-1/2). The peak sensitivity was about 3 10^-21Hz^-1/2. The spectral amplitude is better than 1 10^-20Hz^-1/2 over a band of about 35 Hz. The peak at 935 Hz is a calibration reference signal fed into the d.c. SQUID amplifier to monitor the gain of the electronics.