988 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 60, NO. 2, APRIL 2013 First Performance Results of Ce:GAGG Scintillation Crystals With Silicon Photomultipliers Jung Yeol Yeom, Member, IEEE, Seiichi Yamamoto, Member, IEEE, Stephen E. Derenzo, Fellow, IEEE, Virginia Ch. Spanoudaki, Kei Kamada, Takanori Endo, and Craig S. Levin, Member, IEEE Abstract—A new single-crystal Cerium doped (GAGG) scintillation crystal with high luminosity, high density and relatively fast decay time has successfully been grown. We report on the first performance results of the new GAGG scintillation crystal read out with silicon photomultipliers (SiPM) from Hamamatsu (MPPC) and FBK. The best energy resolution (511 keV peak of Ge-68) of 7.9% was attained with GAGG coupled to MPPC and 9.0% with the FBK SiPM after correcting for non-linearity. On the other hand, the best coincidence resolving time (FWHM) of polished and crystals were and for GAGG crystals compared to and for LYSO crystals respectively with MPPCs. The rise time of GAGG was measured to be 200 ps (75%) and 6 ns (25%) while the decay time was 140 ns (92%), 500 ns (7.7%) 6000 ns (0.3%). Index Terms—Ce:GAGG, gamma-ray spectroscopy, PET, scin- tillators, silicon photomultipliers, SPECT. I. INTRODUCTION A wide range of scintillators are available for the detec- tion of ionizing radiation of which a handful is suitable for use in nuclear medicine, i.e., Position Emission Tomog- raphy (PET) and Single Photon Emission Computed Tomog- raphy (SPECT) [1]–[3]. An ideal scintillator for PET would have high luminosity, high density and effective atomic number, Manuscript received June 16, 2012; revised November 12, 2012; accepted December 06, 2012. Date of publication February 01, 2013; date of current ver- sion April 10, 2013. This work was supported in part by the Stanford Dean’s Postdoctoral Fellowship, Cygnus Fellowship, the AXA Research Fund and in part by the Department of Homeland Security, Domestic Nuclear Detection Of- fice (DHS/DNDO). J. Y. Yeom is with the Molecular Imaging Program at Stanford and Depart- ment of Radiology, Stanford University, Stanford, CA 94305, USA (e-mail: yeomjy@stanford.edu). S. Yamamoto is with the Department of Radiological and Medical Laboratory Sciences, Nagoya University, Nagoya 461-8673, Japan (e-mail: s-yama@met. nagoya-u.ac.jp). S. E. Derenzo is with the Department of Radiotracer Development and Imaging Technology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA (e-mail: sederenzo@lbl.gov). V. C. Spanoudaki is with the Molecular Imaging Program at Stanford and Department of Radiology, Stanford University Stanford, CA 94305, USA. She is now with Koch Institute for Integrative Cancer Research, MIT, MA 02139, USA (e-mail: vspan@mit.edu). K. Kamada and T. Endo are with the Materials Research Laboratory, Fu- rukawa Co. Ltd., Tsukuba 305-0856, Japan (e-mail: {k-kamada, ta-endou}@fu- rukawakk.co.jp). C. S. Levin is with the Departments of Radiology, Physics and Elec- trical Engineering, Stanford University, Stanford, CA 94305, USA (e-mail: cslevin@stanford.edu). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TNS.2012.2233497 TABLE I PHYSICAL AND SCINTILLATION PROPERTIES OF GAGG fast rise and decay time constants, a peak emission wavelength that matches well with the spectral sensitivity of the photode- tector and low non-proportionality. In addition, the scintilla- tion material should be inexpensive to manufacture, non-hy- groscopic, rugged and preferably produce no intrinsic radia- tion. At the present, Lutetium based oxide scintillation crystals like cerium doped lutetium oxyorthosilicate (LSO), lutetium-yt- trium oxyorthosilicate (LYSO) and lutetium gadolinium oxy- orthosilicate (LGSO) are most commonly used in commercial PET systems as they offer the best tradeoffs of the aforemen- tioned factors [4]–[6]. Ceramic Gadolinium Garnet based scintillators also feature high luminosity, high density and relatively fast decay time [7]. This family of scintillators include the cerium doped (GYGAG) scintillator that was re- ported to show good performance for gamma spectroscopy [8]. Recently, a new single-crystal Cerium doped (GAGG) crystal has successfully been grown using Czochraski method [9], paving the way for the production of large and high quality single-crystal ingots. The GAGG scintillator, compared to GYGAG as mentioned above, has the inherent advantage of a higher density and effective atomic number due to the absence of Yttrium atoms, making it an attractive candidate for applications such as PET and gamma spectroscopy where higher energy radiation has to be detected. The properties of GAGG scintillation crystal as reported in [9] and typical values of common scintillators have been summarized in Table I. A photodetector is often used in conjunction with scintilla- tors to convert light photons emitted by the scintillator upon in- teraction with radiation to electrical signals. The silicon photo- multiplier (SiPM), is a relatively new semiconductor photode- 0018-9499/$31.00 © 2013 IEEE