THz Characterisation

1. High Power THz Radiation from ALICE ALICE Short Electron Bunches Short Pulses of Light High Power THz radiation Short electron bunches produced by the photo-injector are further compressed by a dipole chicane. These short bunches will emit high power THz radiation due to coherent enhancement – the wavelength of the light is longer than the bunch. The intensity of this light scales quaderatically with the number of electrons in the bunch. ALICE Short Electron Bunches Short Pulses of Light High Power THz radiation January 2009 - first THz photons detected from Alice The THz intensity scaled quaderatically with bunch charge over a limited range of bunch charge, as expected for Coherent Synchrotron Radiation. Are THz Safe? Could high power THz sources be employed for security screening? World unique facility on Alice will allow high power irradiation of living cells under controlled conditions. Flux at the source How safe are THZ? World unique tissue culture laboratory allows high power THz irradiation of living human cells Wavenumber (cm-1) THz Characterisation The optical system is designed to efficiently transport the long wavelength THz light to the diagnostics room, where its spectrum can be measured with a custom high aperture step-scan Martin-Puplett interferometer developed in collaboration with STFC Space Science. The spectrum will indicate bunch characteristics - length (from the onset of coherent enhancement) and charge (from the intensity). The light can be transported on to a dedicated tissue culture facility. This is a world unique facility and will allow the effect of high repetition high peak power THz irradiation on human cells. Theoretical synchrotron light spectrum from the THz extraction port on ALICE. The model uses an electron bunch length of 1.6 ps FWHM and a bunch charge of 80 pC .