1. Dual-axis, Duo Lateral Position Sensitive Detectors Robin Dienhoffer State University of New York at Oswego Advisor: Dr. Sherry Yennello Cyclotron Institute, Texas A&M University

2. Outline Particle Detectors Silicon Detectors Position Sensitive Detectors now New Position Sensitive Detector

3. Particle Detectors Materials and forms used Solid, liquid & gas Various elements Germanium, Cesium iodide, silicon, plastic… Various Attributes Stopping power ΔE vs. E plots Energy and position resolution Cost Ease of handling Combining Detectors

4. Silicon Detectors Not overly sensitive to humidity and operates well at room temperatures Delicate, but not impossible to handle Still expensive, but becoming more widely used Band Gap

5. Energy difference between valance band and conduction band Silicon is a good material to detect the particles that we work with To get to the conduction band, approximately 2.8 eV are needed To get a readable charge, electrons must be excited enough to “jump” to the conduction band This charge is then collected by the charge collection strips to be converted to signals Valance Band Conduction Band Band Gap

6. What are PSDs? PSD stands for Position Sensitive Detector Collects deposited charge in such a way that the position of the particle can be determined This will allow us a more thorough understanding of the underlying reaction mechanism that produced the charged particles

7. FAUST The Forward Array Using Silicon Technology Currently uses discrete detectors Position information restricted to which detector was hit Hoping to upgrade to PSDs, giving better position resolution

8. Some PSDs in Use Pixilated Detectors Strip detectors that use separated pads of Silicon to detect where the particles hit The number of channels of electronics limit the feasibility of this option Resistive Detectors Dual-axis Tetra-lateral DADL

9. Dual-axis Signal pulled from the edge centers This results in circular pulling that must be adjusted through correcting algorithms

10. Dual-axis Tetra Lateral Dual-axis Tetra lateral detector collects charge at all four of the corners on one face of the detector This causes a pin- cushion effect which must, again, be accounted for using correction algorithm

11. Four Corner PSD – Dr. Tribble’s Group Resistive sheet of Si on front and a non-resistive sheet on the back resistive strips on front edges correct pincushion effect Five signals- four on front and one on back (total energy)

12. Dual-axis, Duo Lateral Dual-axis, duo lateral PSDs collect charge in a way which give position from both the front (horizontally) and the back (vertically). This method will lead to much less distortion than in previous models.

13. F1 F2 B1 B2 Guide wires for charge Front 1 Back 2 Front 2 Back 1 Charge collecting strips

14. Detecting Location Charge Collection Guide Wires L1L1 L2L2 L2L2 L1L1 L2L2 L1L1 Edge 1 Edge 2 When L1 = L2, both edges receive the equal charge, or Q1 = Q2 When L1 > L2, Edge 1 receives less charge, or Q1 < Q2 When L1 Q2

15. /\/\/\ VoVo V1V1 V2V2 V o = V 1 + V 2 Another Perspective

16. Settings Found that biasing the front to 40.0 volts and the back guard ring to 5.0 volts is the most effective to get a clear energy spectra and position graph Shaping time of 1 μs or 3 μs gives both good energy and position resolution

17. 228 Th Energy Spectra 5.432 5.686 6.051 6.288 6.778 8.784

18. 228 Th Position Graph

19. Beam Time: Ag + nat Au ΔE-E Graph Z = 1 Z = 2 Z = 3Proton Deuteron Triton

20. Beam Time: Ag + nat Au Position Graph

21. Hole Ratios MaskMeasured 3 mm250 Chan. 2.5 mm200 Chan. 1.5 mm125 Chan. Red = 1.20, 1.25 Green Red = 0.50, 0.50 Blue Green= 1.67, 1.60 Blue

22. Future Use This PSD design is currently being optimized for the future FAUST upgrade Micron Semiconductor is offering this detector to the scientific community at large

23. Acknowledgements Dr. Sherry Yennello SJY Group REU Program NSF, Grant _____ Robert A. Welch Foundation, Grant A- 1266 DOE, Grant DE-FG03-93ER40773.