1. Ultraviolet Light Sources for LAr Detector Calibration A presentation in which I Consider a Number of Modern Methods of Generating Vacuum Ultraviolet Light (100 - 200 nm) for the purpose of Injecting UV Photons into the LAr to measure the response of the Photon Detection System; Including the Wavelength-Shifting-Medium. Jeremy Danielson, LANL Gus Sinnis, LANL February 2nd, 2013

2. Photon Detection System Heindl et. Al. EPL, 91 (2010) 62002 Gehman et al. Inst. Meth. Astro. (2011) PMT Wavelength Shifter 130nm light

3. What we would like to measure Response of the PDS with: A well-characterized 130nm light source Varying Positions Low Number of Photons

4. Nomenclature – UV/DUV/VUV/XUV UV: Ultraviolet ~10 – 400nm, 3 – 124 eV DUV: Deep Ultraviolet ~200 – 300 nm, 4 – 6 eV VUV: Vacuum Ultraviolet ~10 – 200 nm, 6 – 124 eV XUV: Extreme Ultraviolet ~10 – 100 nm, 12 – 124 eV Liquid Argon Emission: ~130nm / 9.5 eV

5. Challenge – Getting VUV In Window Transmission is Tricky esource Optics

6. Cryogenic Material Issues MaterialThermal Expansion Coefficient Fused Silica0.5 x 10 -6 /K Crystalline Quartz7.07 x 10 -6 /K CaF 2 18.85 x 10 -6 /K MgF 2 13.7 x 10 -6 /K, 8.48 x 10 -6 /K LiF34.4 x 10 -6 /K Challenge – Getting VUV In

7. Sources of VUV Synchrotron Free Electron Laser E-Beams into Ar Plasma Emission Deuterium Lamps Laser-Based Nonlinear Optics

8. Heindl et. Al. EPL, 91 (2010) 62002 Ulrich et. al. 2009 Electron Beams

9. Gas Plasma Emission Carman et. al. ICONN 2010

10. Deuterium Lamp Heraeus Noblelight

11. Coherent Laser Sources High Harmonic Generation Hollow-Core Photonic Crystal Fibers

12. When placed in a strong laser field, a collection of noble atoms can emit high energy photons (10 – 100 eV) Midorikawa 1999 High Harmonic Generation

13. Midorikawa JJAP 2011 This is a three step process: 1 - An electron is pulled from the atom by the intense field 2 - The electron is accelerated by the field. 3 - The electron is rammed back into its parent ion. This process repeats with every optical cycle. Because of the periodicity of the driving field, the emitted UV will only occur at harmonics of the optical beam.

14. High Harmonic Generation Emission typically falls for the first 10 or so harmonics, then is relatively constant until the cutoff at I p + 3.2 U p where I p is the ionization potential U p is the ponderomotive potential (average kinetic energy of an elecron in the field.) This cutoff is generally on the keV scale. Jones et al. PRL 94, 193201 (2005)

15. Sun & Ferrari, Nat. Phot. 2011 A hollow-core waveguide can be used to increase the interaction length of the field and gas High Harmonic Generation

16. Phase Matching Consideration Time Phase Matched Phase Mismatched

17. Popmintchev et al. PNAS 2009 Tuning Phase Matching in a Fiber Varying the gas density tunes the phase matching of the HHG to select various emission regions Steinkellner et al. CLEO 2005

18. Photonic Crystal Fibers Philip Russell, Science 299, 358 (2003);

19. Travers et al. 2011 Hollow Core Photonic Crystal Fibers

20. Hollow Core Photonic Crystal Fibers Have a Number of Interesting Properties Tunable dispersion properties by adjusting structure size and gas pressure. Very small field confinement, ~1 micron; leads to very high fields and good nonlinear effect efficiency. Hollow center allows UV to be transmitted with relatively little absorption. Localization inside the hollow center limits Raman scattering, making soliton formation more favorable. Optical Arrangement is very simple compared to free-space methods.

21. Hollow Core Photonic Crystal Fibers Misoguti et al. Phys Rev. Lett. 2001 Four Wave Mixing in a Fiber

22. Husakou, CLEO/QELS 2010 Soliton Formation Within a PCF (Modeled) 120 nm 800 nm

23. Some Thoughts on Implementation

24. 130nm light has a short Rayleigh scattering length (~90 cm). It would be useful for PDS calibration to be able to introduce VUV light in the interior of the Liquid Argon, not just at the edges. I believe the most promising techniques for getting 130nm photons into the chamber are currently the Deuterium Lamp or one of the fiber-based methods. I suspect that however the light is delivered, we will want to mimic a point source through scattering from a small surface or similar technique. Deuterium Lamp: Common and robust technology. Relatively inexpensive. As an isotropic source, may be a bit tricky to get light to the chamber interior. Fiber-Based Methods: Demonstrated, but still a rapidly evolving research field. The fiber could be a good delivery method into the chamber. Requires an amplified femtosecond laser, which are robust but pricey. Some Thoughts on Implementation

25. Thank You

26. References “The scintillation of liquid argon”, Heindle et al., EPL, 91 (2010) 62002 “Fluorescence Efficiency and Visible Re-emission Spectrum of Tetraphenyl Butadiene Films at Extreme Ultraviolet Wavelengths”, Gehman et al. Instrumentation and Methods for Astrophysics, Sep 2011. “Electron beam induced light emission”, Ulrich et al., Eur. Phys. J. Appl. Phys. 47, 22815 (2009) “Development of incoherent EUV/VUV light sources: tailoring the output pulse characteristics for materials processing applications”, Carman et al. ICONN 2010 “Phase-Matched High-Order Harmonic Generation by Guided Intense Femtosecond Pulses”, Midorikawa et al., IEEE Journal of Selected Topics in Quantum Electronics, 5, (1999) “High-Order Harmonic Generation and Attosecond Science”, Midorikawa et al., Japanese Journal of Applied Physics 50 (2011) 090001 “Phase-Coherent Frequency Combs in the Vacuum Ultraviolet via High-Harmonic Generatio inside a Femtosecond Enhancement Cavity”, Jones et al. PRL 94, 193201 (2005) “Fibre sources in the deep ultraviolet”, Sun et al., Nature Photonics 5 (2011) “Phase matching of high harmonic generation in the soft and hard X-ray regions of the spectrum”, Popmintchev et al. PNAS 106 26 (2009) 10517 “Generation of Femtosecond VUV Pulses Using Four-Wave Difference-Frequency Mixing in an Argon filles Hollow Waveguide”, Steinkellner et al., CLEO Europe 2005 “Photonic Crystal Fibers”, Philip Russell, Science 299, 358 (2003); “Ultrafast nonlinear optics in gas-filled hollow-core photonic crystal fibers”, Travers et al. J. Opt. Soc. Am. B 28 12 (2011)

27. References “Generation of Broadband VUV Light Using Third-Order Cascaded Processes”, Misoguti et al., Phys. Rev. Lett. 87 1 (2001) “Generation of 5-fs pulses tunable from 400 to 120 nm by kagome-lattice hollow-core PCF”, Husakou et al., CLEO 2010