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The SINDRUM-I Experiment
by Ralph Eichler and Christoph Grab
This is not the latest submitted version.
This Submission thread is now published as
Submission summary
| Authors (as registered SciPost users): | Christophorus Grab |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202012_00016v1 (pdf) |
| Date submitted: | 2020-12-23 16:35 |
| Submitted by: | Grab, Christophorus |
| Submitted to: | SciPost Physics Proceedings |
| Proceedings issue: | Review of Particle Physics at PSI (PSI2020) |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Experimental |
Abstract
SINDRUM-I was the first nearly 4 spectrometer at SIN. It was initially designed to 9 search for the forbidden decay + ! e+ee+ , but also successfully studied various 10 other processes with high precision. The upper limit obtained for the branching ratio of B!3e = (+ ! e+ee+ )= (+ ! e+e¯ 11 ) < 1.0 1012(90% CL) from 1988 is still the best. The first statistically significant observation of the rare decay + ! e+ee+e¯ 12 , achieved in 1985, yielded a branching ratio of B13 !3e2 = (3.40.20.2)105. Several 14 othermeasurements of rare decays were undertaken: the first observation of the -decay 15 + !e+eee+ resulted in (+ !e+eee+ )= (+ !+ ) = (3.2 0.5 0.2) 109, 16 also still the best measurement; and a determination of the ratio of the weak axial- to 17 vector-form factor FA=FV = (0.7 0.5), resolving an ambiguity. In addition, upper limits 18 for + ! e+ and + ! e+e with subsequent decay ! e+e (search for "massless" Goldstone bosons) and 0 !e+e 19 < 1.3 107 were obtained.
Current status:
Reports on this Submission
Report 2 by Adrian Signer on 2021-1-14 (Invited Report)
- Cite as: Adrian Signer, Report on arXiv:scipost_202012_00016v1, delivered 2021-01-14, doi: 10.21468/SciPost.Report.2409
Report
We (the editors Cy Hoffman, Klaus Kirch, Adrian Signer) had the opportunity to review an earlier draft of the article and were in communication with the authors before the submission. All our comments and suggestions have been taken into account. Hence, we think the paper can now be published in the current form.
Report 1 by Niklaus Berger on 2021-1-13 (Invited Report)
- Cite as: Niklaus Berger, Report on arXiv:scipost_202012_00016v1, delivered 2021-01-13, doi: 10.21468/SciPost.Report.2405
Strengths
1-Provides an inside perspective of the detector and physics achievements of SINDRUM
2-Clearly lists the measurements performed including motivations and results
3-Places the experiment in its historical context
Weaknesses
1-Does not discuss the limitations of the setup and what motivated the end of the experiment
2-Misses a conclusion
Report
The SINDRUM I experiment was an important step in the history of PSI (then SIN) and has performed many measurements which are world leading to this date. The paper clearly outlines the measurements performed and should clearly be publshed as part of a review of particle physics at PSI. The paper is clearly written and very readable. It starts with the historical motivation, introduces the process $\mu \rightarrow eee$ and then describes the measurements performed and their results. The final sections describe the apparatus and in particular the innovative MWPCs used. I am missing a conclusion, which could also discuss the limitations of the appartus/experimental approach and the reasons why the measurement programme was stopped at the point where it was stopped.
Requested changes
1- Line 13: This sentence is a bit long and the form factor ratio does not really fit topically as it is not obviously a rare decay measurement - maybe you can split this into two.
2- Line 18/Lines 113ff.: I find the use of $\phi$ for the new boson confusing - is there a notation with no overlap with mesons?
3- Line 32: I find the jump from activities triggered in 1977 to experiments planned today very abrupt, maybe this can be expanded by a sentence or two (which would then also allow for cross references to other entries in the volume once this is technically possible)
4 - Line 37: Maybe cite the calculations that lead to this number and also mention the state of knowledge when SINDRUM was conceived
5 - Line 39: .. models of physics beyond...
6 - Line 41: How is this different from today?
7 - In several places in the paper you use "still valid today" for results that are world leading/unique to this day. I suggest stronger wording.
8 - Line 102: a verb seems to be missing
9 - Line 143: surface muon beam
10 - Line 149: 110 cm length
11 - Line 152: z should be italic
12 - Line 170: I find the hyphen in end-printed unhelpful
13 - The end of the paper is very abrupt - one might consider swapping the detector and physics parts or - and this would be my preferred solution- add a concluding paragraph briefly sumarizing the highlights and also mentioning the limitations of the experiment, why it was terminated and what came next. (I was always wondering about the exact relationship between SINDRUM-I and -II)
Author: Christophorus Grab on 2021-02-03 [id 1203]
(in reply to Report 1 by Niklaus Berger on 2021-01-13)“The SINDRUM-I Experiment”
Answers to Referee’s comments and requested changes:
1- Line 13: This sentence is a bit long and the form factor ratio does not really fit topically as it is not obviously a rare decay measurement - maybe you can split this into two. A => RE-phrased
2- Line 18/Lines 113ff.: I find the use of ϕ for the new boson confusing - is there a notation with no overlap with mesons? A => that was the nomenclature customary at that time, and also what was used in the original paper. We decided to keep it.
3- Line 32: I find the jump from activities triggered in 1977 to experiments planned today very abrupt, maybe this can be expanded by a sentence or two (which would then also allow for cross references to other entries in the volume once this is technically possible) A => Added some more info and re-phrased.
4 - Line 37: Maybe cite the calculations that lead to this number and also mention the state of knowledge when SINDRUM was conceived. A => The question on the state of theory is implicitly answered in lines 50ff, where modern models are contrasted with the earlier ones. also added comment about nLFV. Citation added.
5 - Line 39: .. models of physics beyond... A => corrected
6 - Line 41: How is this different from today? A => see added comments in item 4), and further rephrasing.
7 - In several places in the paper you use "still valid today" for results that are world leading/unique to this day. I suggest stronger wording. A => Re-phrased
8 - Line 102: a verb seems to be missing A => corrected
9 - Line 143: surface muon beam A => corrected
10 - Line 149: 110 cm length A => corrected
11 - Line 152: z should be italic A => corrected
12 - Line 170: I find the hyphen in end-printed unhelpful A => corrected
13 - The end of the paper is very abrupt - one might consider swapping the detector and physics parts or - and this would be my preferred solution- add a concluding paragraph briefly summarizing the highlights and also mentioning the limitations of the experiment, why it was terminated and what came next. (I was always wondering about the exact relationship between SINDRUM-I and -II)
A => we added a summary paragraph summarizing and explaning.