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Measurement of Leak Properties of Mu2e/Mu2e-II Tensioned Straws

WILLIAM LEIJA

DR. KEN HELLER

BEN MESSERLY

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Quark mixing: observed

�

Charged lepton mixing: not observed

�AKA “charged lepton flavor violation”, CLFV

�

Neutral lepton (neutrino) mixing (oscillation): observed�

The Standard Model:

-17 Fundamental Particles

All matter around us is composed of two basic types: Quarks & Leptons.

Each group consists of six particles, which are related in pairs, or what is referred to as “generations”.

The lightest and most stable particles make up the first generation, whereas the heavier and less-stable particles belong to the second and third generations

-Currently the best theory to describe the most basic building blocks of the universe.

Theory describing ¾ known fundamental forces (Electromagnetic, weak force, & strong force)

Yet, it is an incomplete theory

And the questions to :

“How does gravity fit within the Standard Model?”

“What is Dark Matter?”

“What is Dark Energy?”

“Why do neutrinos have mass?’

“Where did all the antimatter go if matter and antimatter were made in equal amounts?”

Observed Comes in

How will this lead to answer those questions or predict phenomena? The standard model has predicted (^^) and has been observed

This experiment is looking for ways that the standard Model is WRONG.

But these are where it is right.

Not Observed Comes in

This experiment is looking for ways that the standard Model is WRONG.

And what the Standard Model does not predict is (^^). So, the goal is to either observe this CLFV or not.

And we will be able to this with the use of the tracker.

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CLFV Observation

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The Tracker

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The Panels

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The Straws

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Mu2e Straw Specs

15 μm thick Mylar straws
5 mm diameter
Length from 45 to 120 cm
500 Å of aluminum on both inside and outside
An additional 200 Å of gold on the inside

��The outside aluminization of the Mylar straws act as additional electrostatic shielding and reduces leak rate of straws.

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Mu2e-II

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SIMILAR EQUIPMENT & SETUP AS MU2E
MORE INTENSE MUON BEAM
THINNER STRAWS (AL ONLY, LESS MATERIAL & HALF THE THICKNESS)*
GOAL: MU2E II IS GOING TO DRIVE THE RATE DOWN EVEN FURTHER

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My Project

If the new straws are to be used in Mu2e II then the straws must hold gas.
Question: Will the new straws hold gas under tension?

Possible outcomes of leak rate include:

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Big Leak	>500 (E-5 cc/min)	X
Medium Leak	100-500 (E-5 cc/min)	~
Small Leak	<100E (E-5 cc/min)

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Leak Testing

1. Inflating the straws with CO2

a. Failing inflation means the straws

could not stay inflated

2. Inserting the straws into the

leak testing chambers

a. A GUI/sensor measures CO2 leaving the straw

b. Leak rate > 9 *10^-5 cc/min = fail

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Process

Step 1: Pre-Test the straws

The passing straws assigned to rail
Major failures used for prototype

Difficulties:

Thinner straws -> very delicate
Difficult to find straws that are passing

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Design

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CO2 Endcaps

Hook portion of railing w/ CO2 Endpiece

Bottom & Top of railing

Design

The Cap

The Straw

The Hook

Both the Cap and the Hook have about the same pieces. Both have the CO2 End Piece and Viton Epoxied together (190) and then the brass knuckle epoxied onto the Viton and co2 endpiece (very important that this is epoxied so that it can hold the 800g), and the blue wire stripped and soldered onto the brass knuckle (also very important for holding the straw at tension) and then all together on the endpiece epoxied in the straw. The difference though is the role of each end:

The Cap’s role is to be tied together to the nut on top via the BE-CU wire which helps keep the straw at tension at the top end.

The Hook is a little more complicated than that. One of the issues was finding something that will hold the 800 g weights and be able to stay at that tension when the weights were taken off. I found these metal screws that did not have an opening at the top so I had to get them drilled through to fit the blue wire. Soldering and epoxied remained the same.

Next was hooking up the weight and keeping it at that tension..

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Process

Step 1: Pre-Test the straws

The passing straws assigned to rail
Major failures used for prototype

Challenges:

Thinner straws -> very delicate
Difficult to find straws that are passing

Step 2 : Tension Straws

Some rails were difficult in the chamber
Did the tension hold on the rail?
800 g hung from the bottom
30 secs to 1 min wait

Challenges:

Did my end pieces hold?
Did they break?
Most issues on this step…

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Rail being hung up

Straw being tensioned to 1kg

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Hiccups

Epoxy Issue

Soldering Issue

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Process

Step 1: Pre-Test the straws

The passing straws assigned to rail
Major failures used for prototype

Difficulties:

Thinner straws -> very delicate
Difficult to find straws that are passing

Step 2 : Tension Straws

Some rails were difficult in the chamber
Did the tension hold on the rail?
800 g hung from the bottom
30 secs to 1 min wait

Difficulties:

Did my end pieces hold?
Did they break?

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Step 3 : Test Daily

Some rails were difficult in the chamber
Did the tension hold on the rail?
800 g hung from the bottom
30 secs to 1 min wait

Difficulties:

Almost none

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Leak Test GUI

Raw Data from Leak Test GUI

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ST88043 ST88045 ST88046 ST88050 ST88051 ST88053

Highlight the straws “story”:

ST88045 (white) is having a downward slope- not expected and warrants further testing to see if that straw plateaus or further slopes down which would indicate an issue with the tensioning of the straw.

ST88050 (black) decreasing the whole time and while working with it, the nut at the top of the rail on its last test popped off its epoxied base. This straw I think since its first test, the nut had been breaking away from the epoxied part and as a result had been lowering the tension of the straw which would explain the decreasing leak rate.

ST88046(Red)/ST88053(brown)/ST88043(Neon green) are examples of good data being taken and almost ideally what I hoped to happen (increase and then plateau)

ST88051(Pink)is an example of a straw that shows signs of caution. If this straw’s leak rate would continue to increase, then it would pose an issue that these straws may have.

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Conclusion & What’s Next?

The straws did not show any signs of not being able to be used
The straws show promise in their performance under tension
Unfortunately, I do not have the ability to continue leak testing at Texas State.
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Apply to UMN Grad School
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PROFIT (Nobel Prize here we come)

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1) If the straws are to be used, they will be under tension for years so to continue to take as measurement daily (possibly 2x a day) for as long as possible (months) will give a more accurate description on how the straws will behave when used for the tracker. And tests beyond the standard tension.

2) The straws did not rip, break, collapse, or anything that would otherwise eliminate the possible usage of Al Only straws

3) Since this project was hands on, I don’t think there will be a way to continue what I have done over the school year but what I can do is leave all my data files, straws, instructions, pictures as to what I did so that the next person who is to continue this would be put in the best situation going forward.

Lessons Learned:

Perseverance: research is frustrating most of the time. Dr. Ken Heller mentioned that majority of research is doing the tedious tasks so when working on such endeavors, you wanna pick the one that you can see yourself doing these tedious tasks.
Creaitivity:

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Acknowledgements

National Science Foundation
University of Minnesota, Physics and Astronomy
Advisors: Dr. Ken Heller & Dr. Ben Messerly

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Thank You

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Questions?

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BackUp

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Beyond the Standard Model

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The Tracker: Taking Pictures

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Front End Electronics (FEE)

Data Acquisition Software

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Blue Wire

Beryllium-Copper Wire

Solder Set Equipment & DP190 Epoxy

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Highlight the straws “story”:

ST88045 (orange one) is having a downward slope- not expected and warrants further testing to see if that straw plateaus or further slopes down which would indicate an issue with the tensioning of the straw.

ST88050 (yellow one) decreasing the whole time and while working with it, the nut at the top of the rail on its last test popped off its epoxied base. This straw I think since its first test, the nut had been breaking away from the epoxied part and as a result had been lowering the tension of the straw which would explain the decreasing leak rate.

ST88046(black)/ST88053(purple)/ST88043(white) are examples of good data being taken and almost ideally what I hoped to happen (increase and then plateau)

ST88051(red) is an example of a straw that shows signs of caution. If this straw’s leak rate would continue to increase, then it would pose an issue that these straws may have.