Another method of detection for ERDA is time of flight (TOF)-ERD. This method does not present the same issues, as those for the silicon detector. However, the throughput of TOF detectors is limited; the detection is performed in a serial fashion (one ion in the detector at a time). The longer the TOF for ions, the better the time resolution (equivalent to energy resolution) will be. TOF spectrometers that have an incorporated solid state detector must be confined to small solid angles. When performing HI-ERDA, TOF detectors are often used and/or "∆E/E" detectors-such as ionization chambers. These types of detectors usually implement small solid angles for higher depth resolution. Figure 6, on the left, shows a Time-of-Flight detector commonly used in ERDA. Heavier ions have a longer flight time than the lighter ions. Detectors in modern time-of-flight instruments have improved sensitivity, temporal and spatial resolution, and lifetimes. Hi mass bipolar (high mass ion detection), Gen 2 Ultra Fast (twice as fast as traditional detectors), and High temperature (operated up to 150 °C) TOF are just a few of the commercially available detectors integrated with time-of-flight instruments. Linear and reflectron-TOF are the more common instruments used.