The Heidelberg Heavy Ion Postaccelerator

The Heidelberg Heavy Ion Postaccelerator, a linear accelerator booster for the upgraded MP-Tandem is operational in its extended version since end of 1979. Yielding 9.7 MV in CW and 18.5 MV in pulsed mode (duty factor 0.25) it has considerably increased the mass and energy range of heavy ions for Nuclear Physics experiments at Heidelberg. The high flexibility of the booster is guaranteed by using 32 independently phased spiral resonators allowing operation of the machine in the mass range of A=10 to A=100 with almost constant accelerating voltage; although even ions as heavy as 197Au have been successfully postaccelerated. Typical examples of postaccele-rated beams are: 164 MeV 12C, 332 MeV 32S, 476 MeV 79Br, 511 MeV 127J and 640 MeV 197Au. Longitudinal and transversal beam quality are tandem like with ¿r < 2¿ mm mrad and ¿l < 3.2¿ MeV .deg., the debunched energy resolution being well below 10-3. The overall availability of the postaccelerator together with the MP-Tandem was 83% of the scheduled user beam time in 1980.