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TZID:Europe/Rome
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TZOFFSETFROM:+0100
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DTSTART:20180325T010000
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DTSTART:20181028T010000
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DTSTART;TZID=Europe/Rome:20181129T110000
DTEND;TZID=Europe/Rome:20181129T130000
DTSTAMP:20260910T205108
CREATED:20181106T184755Z
LAST-MODIFIED:20181206T184904Z
UID:13711-1543489200-1543496400@w3.lnf.infn.it
SUMMARY:Terahertz Driven Electron and X-ray Sources
DESCRIPTION:Today\, high brightness and highly relativistic electron beams are generated by circular or linear accelerators (LINAC) typically operating with 1-3 GHz accelerating frequencies and approaches towards X-band frequencies in the 10 GHz range are maturing. The achievable accelerating gradients are limited by field emission from cavity walls or pulsed heating to several tens of MV/m in the case of low frequencies and up to 100 MV/m in the case of X- band frequencies. Moving up in frequency to the THz range\, here hundreds of GHz\, experimentally confirmed scaling laws predict the realization of few-hundred MV/m to 1 GV/m accelerating fields in LINACs and guns\, respectively. The high field strength and field gradients enable direct generation of single femtosecond electron bunches with substantial charge in the pC-range from very compact devices. We will discuss highly efficient laser based THz generation by optical rectification and first results towards THz based electron guns\, LINACs and beam manipulations with the final goal to construct a hard-X-ray source producing attosecond pulses.
URL:/event/terahertz-driven-electron-and-x-ray-sources/
LOCATION:Aula Salvini
CATEGORIES:Seminari generali
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DTSTART;TZID=Europe/Rome:20181129T143000
DTEND;TZID=Europe/Rome:20181129T163000
DTSTAMP:20260910T205108
CREATED:20181113T184830Z
LAST-MODIFIED:20181206T184904Z
UID:13833-1543501800-1543509000@w3.lnf.infn.it
SUMMARY:γγ scattering and non-BFKL contribution to Pomeron
DESCRIPTION:Abstract: Pomeron is a term introduced in the 1960’s in the frame- work of the phenomenological Regge theory. It describes the behavior of total cross-sections of any hadronic reaction at extremely large values of the invariant energy s. In the QCD context\, the best-known contribution to the Pomeron comes from the BFKL equation This approach resums Leading Logarithmic (LL) contributions i.e. single-logarithmic (SL) contributions\, ∼ (αs ln s)n\, multiplied by the overall factor s. The high-energy asymptotics of this resummation is known as the BFKL Pomeron. It predicts the total cross-section of hadronic reactions (and the γγ-scattering in particular) to behave\, asymptotically\, as ∼ s∆\, where the exponent ∆ is called the intercept of the BFKL Pomeron.\nIn contrast\, we calculate amplitude ADL of elastic γγ-scattering in the Double-Logarithmic approximation (DLA)\, accounting for contributions ∼ (αs ln2 s)n. They are not accompanied by the overall factor s\, so asymptotics of ADL is ∼ s(∆DL−1) which looks negligibly small compared to the BFKL result. By this reason the DL contribution to Pomeron was offhandedly ignored by theoretical HEP society and full attention was focused on the BFKL Pomeron only. However\, we demonstrate that the intercept ∆DL proves to be so large that its value compensates for the lack of the extra factor of s and makes the DL Pomeron of comparable importance to the BFKL Pomeron. It means that DL Pomeron should participate in theoretical analysis of all HEP results where the BFKL Pomeron has been involved.
URL:/event/%ce%b3%ce%b3-scattering-and-non-bfkl-contribution-to-pomeron/
LOCATION:Aula A-1\, Via Enrico Fermi\, 40\, Frascati\, Roma\, 00044\, Italia
CATEGORIES:Seminari teorici
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