Laser Acceleration of Protons from Thin Film Targets

Authors

• K. Flippo, Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Ml
• Sudeep Banerjee, Center for Ultrafast Optical Science, University of Michigan, Ann ArborFollow
• V. Yu. Bychenkov, P. N. Lebedev Physics Institute, Russian Academy of Science, Moscow, Russia
• S. Gu, Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Ml
• Anatoly Maksimchuk, University of MichiganFollow
• G. Mourou, Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Ml
• K. Nemoto, Central Research Institute of Electric Power Industry, 2-11-1, Iwado-kita, Komae-shi, Tokyo
• Donald P. Umstadter, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

11-20-2001

Comments

9th Workshop on Advanced Accelerator Concepts, P L. Colestock, S. Kelley, eds., AIP Conference Proceedings, No. 569 (AIP Press, New York, 2001) p. 553-562. Copyright 2001. Permission to use.

Abstract

A collimated beam of fast protons, with energies as high as 10 MeV and total number of 10⁹, confined in a cone angle of 40°±10° has been observed when a 10 TW laser with frequencies either ω₀ (corresponding to 1 μm) or 2ω₀ was focused to an intensity of a few times 10¹⁸ W/cm² on the surface of a thin film target. The protons, which originate from impurities on the front side of the target, are accelerated over a region extending into the target and exit out the backside in a direction normal to the target surface. Acceleration field gradients of ~10 GeV/cm are inferred. The maximum proton energy for 2ω₀ can be explained by the charge-separation electrostatic-field acceleration due to "vacuum heating." In other set of experiments when a deuterated polystyrene layer was deposited on a surface of a Mylar film and a ¹⁰B sample was placed behind the target, we observed the production of ~10⁵ atoms of positron active isotope ¹¹C from the nuclear reaction ¹⁰B(d,n) ¹¹C.