[PEPPo] [EXTERNAL] Re: Radiation in oriented crystals: Innovative application to future positron sources

[Eric Voutier]

 Hello Jay,
 
 The technique would work but electron channeling do not give polarized photons, so you loose positron beam polarization. The only way to get polarized positrons at CEBAF is direct production from the electron beam within a unique target. A 2 target scheme where you would produce first polarized photons (by bremmstrahlung, not channeling) and then polarized electrons in a second target is just not efficient enough.  Some years ago, I was looking at the direct production of positrons from the 12 GeV beam with the idea of a new tunnel parallel to the hall B one. It was working for hall B intensities and having usefull beam energies up to 6-8 GeV and only 1 hall... far from what we already have now.

 Best, Eric  

----- Mail original -----
De: "Jay Benesch via PEPPo" <peppo at jlab.org>
À: peppo at jlab.org
Envoyé: Mardi 9 Janvier 2024 13:31:43
Objet: [PEPPo] Radiation in oriented crystals: Innovative application to future positron sources

I've just skimmed this and it gave rise to an out-of-the-box idea: could 
this be placed in the BSY, creating the positrons there?  All energies 
to ~20 GeV would then be available.  ABC could all get positrons. 
Shielding would be a big issue and might preclude it.


https://urldefense.proofpoint.com/v2/url?u=https-3A__arxiv.org_abs_2401.03886&d=DwIFaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=JlUFXKjU497y48k9NKRpBw&m=WQre3hoW4nZvhcGNBBsSbIBDsN6wLnB10IIV30cq4bJMMGwQ88zY48AEwYtk_VGz&s=5g7bJOk7qxjH3RX4U3MAyK50j7evp6KQoVD4wVCae1Y&e= 

Mattia Soldani, Fahad Alharthi, Laura Bandiera, Nicola Canale, Gianluca 
Cavoto, Iryna Chaikovska, Robert Chehab, Vincenzo Guidi, Viktar 
Haurylavets, Andrea Mazzolari, Riccardo Negrello, Gianfranco Paternò, 
Marco Romagnoni, Alexei Sytov, Victor Tikhomirov

It has been known since decades that the alignment of a beam of 
high-energy electrons with particular crystal directions involves a 
significant increase of bremsstrahlung radiation emission. This 
enhancement lies at the conceptual foundation of innovative positron 
source schemes for future lepton colliders. In particular, the so-called 
hybrid scheme makes use of a heavy-metal radiator in crystalline form, 
which is then followed by an amorphous metallic converter for positron 
generation from electrons by means of a two-step electromagnetic 
process. This work presents the most recent simulation results obtained 
on the development of a hybrid positron source for the FCC-ee from the 
standpoint of the features of both the crystalline radiator and the 
amorphous converter.

Subjects:	Accelerator Physics (physics.acc-ph); High Energy Physics - 
Experiment (hep-ex)
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