Dense Pair and Gamma-Ray Creation Using Ultra-Intense Lasers (Final Technical Report)
- Rice Univ., Houston, TX (United States)
Lasers with intensity >1.4x1018W.cm-2 irradiating solid targets couple 10-50% of its energy to “hot electrons” near the critical surface, with temperature kT > mc2. When these hot electrons impact high-Z target ions (e.g. Au, Pt), they emit copious bremsstrahlung gamma-rays and create e+e- pairs via the Trident process. For targets thicker than ~0.1mm, the gamma-rays create secondary pairs via the Bethe-Heitler processes. The concept of using lasers to create pairs was first studied by Shearer et al (1973). Motivated by the rapid advance of short-pulse ultra-intense lasers based on chirped-pulse amplification, Liang (1994) first proposed irradiating solid Au targets with laser intensity ≥1020W.cm-2 to create dense e+e- pairs. Using particle-in-cell (PIC, Birdsall and Langdon, 1991) simulations, Liang et al (1998, 2002) estimated that high-energy PW lasers can in principle achieve ultra-high in-situ pair densities. Subsequent studies supported this idea and found that for gold foils thicker than ~50 μm, the pair yield is dominated by the Bethe-Heitler (BH, Heitler 1954) process. Cowan et al (1999, 2000) using the LLNL Nova PW-laser to irradiate 125μm gold foils first observed pair creation, followed by Chen et al (2009) who demonstrated copious BH pair creation using the Titan, Omega-EP and Orion lasers. However, the emerging e+/e- ratio of these experiments was ≤ few %, and the pair density was only 1013/cc so that the pair jet transverse size R(~mm) was < pair skin depth c/ω+(=8πn+e2/m)1/2). This was insufficient to qualify as a bona fide ”pair plasma”.
- Research Organization:
- Rice Univ., Houston, TX (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- DOE Contract Number:
- SC0016505
- OSTI ID:
- 1755377
- Report Number(s):
- DOE-RICE-16505; TRN: US2214933
- Country of Publication:
- United States
- Language:
- English
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