# Presentation: 802341

##  e  Conversion Experiment at Fermilab

-  e  Conversion Experiment at Fermilab

- Goal & Motivation
- Requirements
- Recent History – MECO
- Fermilab Scenario
- Beam Parameters
- Status

## GOAL & MOTIVATION

**GOAL**:  Achieve a single event sensitivity  Re = 2  10-17  Present limit from SINDRUM II:  Re  <   4.3  10-12  (90% CL)
**MOTIVATION:**
- We know there is lepton flavor violation (LFV) in the neutrino sector. Is there observable (non-SM) LFV in the charged lepton sector ?
- Sensitive to a broad range of new physics: Supersymmetry, Compositeness, Heavy Neutrinos, Extra Higgs, Leptoquarks, Heavy Z’, Anomalous Z couplings, ...
- Example: In MSSM Re sensitive to off-diagonal elements in the slepton mixing matrix and Re > 10-17  for most of the viable parameter space  GOOD CHANCE OF DISCOVERY

## REQUIREMENTS

- Low energy bunched muon beam providing  ~1018 muons per year. This requires ~1020 primary 8 GeV protons per year.
- Bunch lengths short compared to the lifetime of muons orbiting a nucleus (1.1 s), with a bunch spacing longer than this time.
- Experimental signature: mono-energetic electron & nothing else.To minimize backgrounds, when there is no incoming primary beam there must be no beam at the level of 1 part in 109.
- _Ideal Bunch Structure for a MECO-like Experiment_:

**CW**

- << 1 s

- ~ 1 – 2 s

## RECENT HISTORY – MECO PROPOSAL

- 4  1020 primary protons
- at 8 GeV yield 1  1018
- stopping muons

- 8 GeV
- PROTONS

- Stop muons in a thin target and look
- for a single mono-energetic electron

**Pion production**
**& capture**

**Decay Channel****Momentum ****& sign****selection**

- Well developed design,
- reviewed for  cost & feasibility

## FERMILAB SCENARIO

-  Use 4 Booster batches every MI cycle
-  Momentum stack in the Accumulator
-  Transfer to the Debuncher, rebunch and slow extract

-  Use 18 Booster batches every MI cycle
-  Momentum stack 3 at a time in the Accumulator
-  Transfer momentum stacked batches to the Recycler
-  Repeat until all 18 batches in the Recycler (boxcar stacking)
-  Inject into MI

- FUTURE NuMI PROGRAM

- FUTURE Muon PROGRAM

- 22 Booster batches / 1.467s MI cycle used as follows:

- 4 Booster batches / MI cycle  1013 protons/sec

## PROTON SOURCE RING USAGE

- Booster Batches

- Accumulator

- Recycler

- Debuncher

- 22 cycles = 1467 ms

- 4.61012 p/batch

- 44.61012 p/1467ms =  12.5 1012 p/sec

- 56 1012 p/sec

- 0.1s

- 1.367s

- NEUTRINO PROGRAM

- MUONS

- (NuMI +Muons)

- (NuMI)

- (Muons)

## PROTON BEAM SPECS

| Beam Energy | 8 GeV |
| --- | --- |
| Bunch Trains / sec:  fTRAIN | 0.682 |
| Bunch Spacing:   TB | 1.6 s |
| No. of bunches/train:   NB | 85×104 |
| No. protons/bunch:  nP | 2.16  107 |
| Bunch Length (2.5) : tB | 150 ns  (ns) |
| Protons/train | 1.84  1013 |
| Protons/year (107 secs) | 1.25  1020 |

- Example:  4.6  1012 protons per Booster Batch & a 1.467s MI cycle

- Four years running  5  1020 protons  1.3  1018 stopped muons

## TECHNICAL ISSUES

- Booster to Accumulator Transfer Line  ( also needed for the future neutrino program in the proton plan).
- Radiation limits in the Antiproton Source (same as for NuMI program).
- Slow Extraction
- Debuncher Beam Dump Location
- Rebunching
- Extinction Factor
- Experiment Location

## STATUS

- A substantial fraction of the MECO Collaboration are interested in a   e conversion experiment at Fermilab, if there is a possibility.
- A group of Fermilab scientists are also interested, and have been exploringthe beam options.
- No show stoppers have been identified, and it seems possible there is an attractive solution that would enable a   e  conversion experimentto run at Fermilab in parallel with the neutrino program.
- A meeting is being planned at Fermilab (Sept 15-16) to bring together people interested in the experiment, and review the beam possibilities and experiment design. If an attractive option is identified, this meeting might be an important step towards forming a collaboration and writing an LOI.