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muCool: muon cooling for high-brightness μ+ beams
by Aldo Antognini and David Taqqu
This Submission thread is now published as
Submission summary
| Authors (as registered SciPost users): | Aldo Antognini |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202105_00041v2 (pdf) |
| Date accepted: | 2021-08-04 |
| Date submitted: | 2021-07-28 08:21 |
| Submitted by: | Antognini, Aldo |
| Submitted to: | SciPost Physics Proceedings |
| Proceedings issue: | 15th International Symposium on Radiative Corrections: Applications of Quantum Field Theory to Phenomenology (RADCOR2021) |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Experimental |
Abstract
A number of experiments with muons are limited by the poor phase space quality of the muon beams currently available. The muCool project aims at developing a phase-space cooling method to transform a surface μ+ beam with 4 MeV energy and 1 cm size into a slow muon beam with eV energy and 1 mm size. In this process the phase space is reduced by a factor of 10^9 − 10^10 with efficiencies of 2 · 10^−5 − 2 · 10^−4 . The beam is then re-accelerated to keV-MeV energies. Such a beam opens up new avenues for research in fundamental particle physics with muons and muonium atoms as well as in the field of μSR spectroscopy.
Author comments upon resubmission
we agree with all the comments of the referee. All of them have been taken into account in this resubmission.
Many thanks and best regards
Aldo Antognini
List of changes
1) Referee:
For me it would be helpful if some typical numbers are given for ω, ν and the He densities at 4 and 12 K, so that the interplay between the different regimes in eq.30.1 becomes evident.
Our reply:
We inserted typical values of the requested frequencies. See lines 60-64.
"At lower densities (top part of the target) the collision frequency ν ≈ 3 GHz is smaller than the cyclotron frequency ω ≈ 4 GHz and therefore vD is dominated by the Eˆ × Bˆ term in (30.1). Hence, the muons that are stopped in the top part of the target move downwards (in −y-direction) while drifting in +x-direction. By contrast, at larger densities (bottom part of the target) the collision frequency ν ≈ 55 GHz is larger than the cyclotron frequency ω."
2) Referee
line 81: track -> traces?
Our reply:
Both terms are correct.
3) Referee:
electric field -> homogeneous electric field?
Our reply:
We have inserted "homogeneous". See line 81.
4) Referee:
Fig. 30.3 Though shown on the ordinate, perhaps mention explicitly that muon decay has been divided out.
Our reply:
We have inserted explicitly a comment that the counts are lifetime compensated. See last sentences of figures 30.3 and 30.2 captions.
5) Referee:
line 120. Please explain why z length is limited in the combined scheme.
Our reply:
We inserted following short explanation at lines 121-123.
"Its major downside is the shorter active region in z−direction which is limited by the time needed for the longitudinal compression at the much higher gas density compared to the scheme in the original proposal with longitudinal compression at room temperature."
6) Referee:
30.5 It would be helpful to separate more clearly between demonstrated steps and additional steps still under active R&D in the overall project.
Our reply:
All the steps described in Section 30.5 are active R&D and not yet demonstrated. So following the advice of the referee we have slightly modified the text accordingly:
- Line 133: "We plan to define...."
- Line 140: "A small electrode could be located..."
- Line 145: "Alternatively, the muon could be re-accelerated..."
7) Referee:
table 30.1. Is muon decay accounted for in the first 5 us?
Our reply:
Yes. To avoid possible doubts we specify more clearly the second entry of the table as
"Compression towards the orifice including muon decay losses (within 5 μs)"
Published as SciPost Phys. Proc. 5, 030 (2021)