This document presents the design and preliminary per- formance characterization of a compact yet powerful small animal PET based on Silicon Photomultiplier (SiPMs) photo- sensors and monolithic scintillators. The system capabilities allow the accurate determination of all three spatial coordinates of the gamma photon interaction within the detector crystal. As a result, submillimetric spatial resolutions are possible with no special corrections and using the full field of View (FOV) of the system. Two systems have been evaluated: a single ring with a 46 mm axial FOV and a triple ring with a 148 mm axial FOV. Both designs have an 80 mm transaxial FOV. The design will allow the PET detector to be located in-line with either MRI or uCT as well as supporting simultaneous PET-MR imaging. Design and Technology Detectors The axial and transaxial FOVs of the three ring assembly are approximately 148 mm and 80 mm, respectively. The one ring version features the same transaxial FOV but a reduced axial FOV of 46 mm. The gap between adjacent scintillators has been reduced to only 0.5 mm, providing an almost closed octagonal scintillation volume. Each array is made up by 144 SiPMs, arranged in 12 by 12 rows and columns, covering an active area of approximately 50×50 mm 2 . A single LYSO scintillation block with a thickness of 10 mm has been coupled to each SiPM array. In contrast to previous Albira generations, the entrance surface of this scin- tillator is increased from 40×40 mm 2 to about 48×48 mm 2 , with an exit face of 50×50 mm 2 . The increase in sampling from the previous Albira (12×12 compared to 8×8) allows for better determination of the light distribution. Thus, the known edge effect in continuous crystals is significantly reduced and the determination of the position of the impinging event greatly increased. Black paint has been applied to the entrance and lateral faces of the crystal to pre- serve the scintillation light distribution. Next Generation of the Albira Small Animal PET Based on SiPM Detectors and Continuous Crystals Author: A González 1 , C Correcher 2 , C Molinos 2 , JM Benlloch 1 , S Junge 3 and T Bruckbauer 4 1 I3M Valencia, 46022, SPAIN, 2 Oncovision, Valencia, 46013, SPAIN, 3 Bruker BioSpin GmbH, Ettlingen, Germany, 4 Bruker BioSpin Corporation, Billerica, MA 01821 ,USA Figure 1 Left, one ring PET system made up by 8 detectors. Right, three ring PET system.