1. Alternative Prototype Detector Design D. Reyna Argonne National Lab

2. 18 May 2006D. Reyna -- Argonne National Lab2 Current Designs SANDS –Single volume design Cheap and compact –Maximal edge effects Energy leakage Poor n-capture efficiency Conservative (DC type) –Three volume design High efficiency and good attenuation of singles backgrounds –High resource cost Large area requirements Large number of PMTs

3. 18 May 2006D. Reyna -- Argonne National Lab3 Consider Reflectivity Considered for Double Chooz as a way to reduce the number of PMTs –Main negative is a loss of vertex reconstruction Consideration for a small detector –Vertex resolution is not much better than the dimensions of the detector –Would improve uniformity of response –Could reduce total PMT count to save cost Is one ended readout possible?

4. 18 May 2006D. Reyna -- Argonne National Lab4 Single Ended Readout? Could Reduce footprint by 1.5 – 2 meters Reduce height by 60- 90 cm. Significant reduction in number of PMTs Problem: Long path lengths for reflected light Target Gamma Catcher Mineral Oil Buffer

5. 18 May 2006D. Reyna -- Argonne National Lab5 Focusing Design Target Gamma Catcher Mineral Oil Buffer

6. 18 May 2006D. Reyna -- Argonne National Lab6 Maximum Path Length? Consider the Spherical Detector 500 t1000 t Target Radius4.92 m6.2 m Gamma Catcher Radius 5.27 m6.55 m Maximum Path through Scintillator 10.19 m12.75 m

7. 18 May 2006D. Reyna -- Argonne National Lab7 A 2 ton Detector 1.3m 1.5m 0.35m 2m 1m  Maximum Photon Path Length in Scintillator  = 10.5°10.19m  = 10°10.48m  = 6.5°12.65m  = 6°13.10m

8. 18 May 2006D. Reyna -- Argonne National Lab8 Implementation in GLG4Sim 24 PMTs: placement has not been optimized

9. 18 May 2006D. Reyna -- Argonne National Lab9 Neutron Capture Sample Photoelectrons ~200 pe/MeV Gd Capture 20K events

10. 18 May 2006D. Reyna -- Argonne National Lab10 N-Capture Efficiency (radius)

11. 18 May 2006D. Reyna -- Argonne National Lab11 n-Capture Efficiency (z position)

12. 18 May 2006D. Reyna -- Argonne National Lab12 Final Thoughts Design shows promise Could present a way to be cheap and compact Pursuing ANL funding to investigate scale prototype of this design –Would be nice to have multiple prototypes to compare Recommend that Brazil remain with conservative design