NSSDCA ID: 1972-065A-02
Mission Name: OAO 3The University College London/Mullard Space Science Laboratory experiment used three grazing-incidence paraboloid mirror systems and one collimated proportional counter to observe celestial X-ray sources between 1 and 70 Angstroms. Between 1 and 3 Angstroms, the collimated proportional counter was used in conjunction with pulse-shape discrimination to reject background counts. The window was 0.51-mm beryllium, and the whole area of 17.8 sq cm collected radiation from a source on the axis of its collimating tube. From 3 to 9 Angstroms and 6 to 18 Angstroms, proportional counters located at the focus of two grazing-incidence reflecting telescopes, whose photon collect areas were 5.5 sq cm and 12.5 sq cm, respectively, were used with an anticoincidence scintillator also employed to reject background cosmic-ray counts. Their stellar windows were 3 mm in diameter and were of 76-micron beryllium and 5-micron aluminium, respectively. A channel photomultiplier, located at the focus of a grazing-incidence telescope with a photon collecting area of 23 sq cm, was used to observe between 20 and 70 Angstroms. The channel photomultiplier suffered from high UV background, and provided no useful data. A six-channel pulse-height analyzer could be switched to any of the three proportional counters to improve the energy resolution. An image scanning photomultiplier tube behind a three-element lens of 610-mm focal length was an auxiliary system for measuring misalignments of the Mullard experiment from the pointing direction of the spacecraft and the Princeton spectrometer. The 3 to 9 Angstroms and 6 to 18 Angstroms systems became inoperable in June 1973 when the background shutter stuck in the closed position. Most of the observations after this were made with the 1 to 3 Angstroms system. For more details, see J. A. Bowles et al., J. Phy. E-Sci. Instru., v. 7, p. 183, 1974.
Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office
Name | Role | Original Affiliation | |
---|---|---|---|
Mr. P. W. Sanford | Other Investigator | University College, London | |
Sir Robert L. F. Boyd | Principal Investigator | University College, London |