Vibration Analysis of a Cryocooler for CDMS

1. Vibration Analysis of a Cryocooler for CDMS Lauren Coutant SULI, summer 2007

2. What is CDMS? • Cryogenic Dark Matter Search (CDMS) • It is known that dark matter exists [1] • Best theory: it is Weakly Interacting Massive Particles (WIMPs) [2] • CDMS is a direct detection experiment • Detects the energy transferred when a WIMP has a collision with a nucleus in the detector • Detector is kept at 50mK with a Gifford McMahon cryocooler and dilution refrigerator

3. Two Types of Cryocoolers • Gifford-McMahon (GM) • Uses a piston to push the working fluid through the system • Piston is located in the cryocooler • Pulse Tube (PT) • Uses orifice and reservoir instead of piston • Has no moving mechanical parts inside the cryocooler [3] [4]

4. Stirling (GM) versus PT Cycle Stirling Pulse Tube [5]

5. Potential Problems from Cryocooler • All Cryocoolers have some vibration • Vibration can cause • Heat • Electrical noise, ~T5 • “Vibration free” • Vibration on the order of background seismic motion [6]

6. What Causes the Vibrations? • GM • Piston causes motion in the system • PT • Fluid traveling through impedances—think of musical instruments • Both • Pressure changes of the working fluid cause pipes to deform—think of blood vessels [7]

7. Which one is better? [8] p. 314

8. What type was tested here? • Cryomech Pulse Tube 415 • Two Stage • 1st Stage of the Cryocooler--room temperature to 77K • 2nd Stage--77K to 4K [9]

9. Vibration Analysis

10. Accelerometer Adapted from [10] • Piezoelectric material experiences charge separation when a force is applied • Voltage can be measured and related to the magnitude of the force • Force can be used to find acceleration, F=ma

11. Vibration Testing: Accelerometer Location

12. Vibration Testing: Block Diagram

13. Vibration Analysis: Lab 3 Set up

14. Results As a reference, g=9.8 m/s^2

15. Comparison • How does this relate to what Tomaru’s group got? • How does this relate to the performance of the current CDMS cryocooler?

16. Vibration Reduction Methods • Distance • Cold head placed away from cryocooler [3] • Was implemented in Lab 3 • Flexible material to absorb vibrations • Rigid material to resist elastic deformation • Active vibration cancellation

17. Vibration Reduction Methods: Materials and Counter-weight Adapted from [11] p. 118

18. Vibration Reduction Methods: Distance and Materials [8] p. 310

19. Vibration Reduction Methods: Flexible and Rigid Materials [12]

20. Vibration Reduction Methods: Flexible Connectors Currently in use at Soudan CDMS site.

21. Vibration Reduction Methods: Flexible Connectors

22. Vibration Reduction Methods: Active Cancellation [13]

23. Vibration Reduction Methods: Active Cancellation Single Pipe Four Pipes Six Pipes [7]

24. Conclusions • Vibration of PT415 should be less than current GM cryocooler at Soudan • More analysis needs to be done • Any of the suggested methods of reduction could be applied. • Adding flexible materials--least work, but also least reduction • Active cancellation--work intensive, but great reduction, may not dampen vibrations at high frequency

25. Works Cited • Reisetter, Angela. “Results from the Two-Tower Run of the Cryogenic Dark Matter Search.” University of Minnesota. 2005. • “SuperCDMS Development Project.” SuperCDMS Collaboration. Proposal to DOE and NSF. 2004. • Radebaugh, Ray. “Development of the Pulse Tube Refrigerator as an Efficient and Reliable Cryocooler.” Institute of Refrigeration, London. 2000. <http://cryogenics.nist.gov/Papers/Institute_of_Refrig.pdf>. • Courtney, Bill. “Cryocoolers-Refrigerators producing very low temperatures” Accessed on 6-15-2007. <http://www.cheshire-innovation.com/news/cryocooler/htm> Cheshire Innovation. • Yuan, Sidney. “Pulse Tube Coolers (Cycle, Engines, Cryogenics Refrigerators, Cryocoolers).” <http://www.yutopian.com/Yuan/PT.html> 2000. • Uchiyama, T., K. Kuroda, M. Ohashi, et al. “Present status of large-scale cryogenic gravitational wave telescope." Classic Quantum Gravity V 21. 13 Feb. 2004: p. 1161-1172.“Cryomech PT415.” Cryomech, Inc. 2007. <http://www.cryomech.com/DEVELOPMENTS/PT415.htm> • Suzuki, T., T. Tomaru, T. Haruyama, et al. "Ultra-Low Vibration Pulse Tube Cryocooler with a New Vibration Cancellation Method ." Advances in Cryogenic Engineering: Transactions of the Cryogenic Engineering Conference. V. 51. 2006 American Institute of Physics. • Tomaru, Takayuki; Toshikazu Suzuki; Tomiyoshi Haruyama; et al. "Vibration analysis of cryocoolers." Cryogenics. V44, 2004. p. 309-317. • “Cryorefrigerators: Pulse Tube.” Cryomech Inc. 2007. <http://www.cryomech.com/PULSE%20TUBES.htm> • “Function of Piezoelectric Accelerometers.” PCB Piezotronics. PCB Group, Inc. 2007. <http://www.pcb.com/ techsupport/tech_accel.php>. • Veprik, A.M., S.V. Riabzev, G.S. Vilenchik, et al. “UItra-Iow vibration split Stirling linear cryogenic cooler with a dynamically counterbalanced pneumatically driven expander.” Cryogenics. V4, 2005. p 117-122. • Tomaru, Takayuki; Toshikaza Suzuki; Tomiyoshi Haruyama; et al. “Development of a Vibration-Reduction System of Cryocooler for a Cryogenic Interferometric Gravitational Wave Detector.” • Suzuki, T., T. Tomaru, T. Haruyama, et al. "Pulse Tube Cryocooler with Self-Cancellation of Cold Stage Vibration." Cryo Prague 2006. <http://arxiv.org/abs/physics/0611031>.