Laser cooling of C2− for

ultra cold antiprotons

Narita Kanako

Supervisor: Michael Doser

1

About me

• At HomeMaster in Particle Physics

Searching for hidden photons at

The University of Tokyo

• At CERNLock-in measurement for photo-electrons from anion molecules

AEGIS,ES-SME

My working place

2

What is AEGIS experiment?

• Goal: Study gravitational interaction of antimatter with matter, searching for violations of CPT theorem and weak equivalence principle

•Antihydrogen production via resonant charge exchange

Antihydrogen production:

→Requires ultracold antiprotons

3

How to cool antiprotons

• Idea: Sympathetic cooling of ҧ𝑝 by laser cooling of anions

• Use of C2− anions because of well known level scheme

• Laser cooling of C2− in Penning trap cools ҧ𝑝 to 𝑻 ҧ𝒑 ≈100 mk

• C2− has to be in the ground state for cooling

I am studyingtrapping and cooling C2

−

Experimental equipment for cooling

4

What am I actually doing at AEGIS?

My study:To make a program to check if there was a signal on the MCP cameraPurpose:To know that the laser was on the resonance with the C2

−

photodetachment transitionTo verify whether C2

− is in the ground state

Trapping C2− 3MHz

@ 120 V

C2− flying to the trap

Photo electronkicked out radially from the trap to the detectorMCP camera

Detector/MCP camera

5

What am I actually doing at AEGIS?

Time [us] Time [us]

Function generator’s signal MCP’s signal

The trap radio frequency is driven by the function generator.When the function generator signal goes from 0 to 1, a recording is triggered, where the time is noted and the corresponding MCP signal in the same time is recorded for a period of 100ns.This MCP data is just the background data, without any lasers or C2

−. The final MCP data will be recorded later.

Voltage[V] Voltage[V]

6

Result

0.001547

0.006187

0.000885

0.002431

-0.001325

0.003093

0.00243

-0.001325

0.0030940.00265

-0.002

-0.001

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

1 2 3 4 5 6 7 8 9 10

The average value of background dataVoltage[V]

Event number

We picked up the MCP back ground signals corresponding to signals going up in function generator. The final MCP data will be recorded later. 7

Summary

• We did Lock-in measurement for photo-electrons from anion molecules.

• I made a program to select signals according to photo-electron signals.

• The final MCP data will be recorded later.

• I thank Drs. Michael Doser, Sebastian Gerber, Christian Zimmer and Emanuel Oswald for their support.

8

Thank you for your attention. Questions?

9

Back up

10

What is AEGIS experiment?

Studies:

Gravitational Acceleration of Antihydrogen

How it works:

Observes the pattern produced by parallel beams of excited low-energy antihydrogen atoms as they pass through 3 gratings

11

Why is the amplitude of function generatorlower ?

• Shortly before the rf cable reaches the trap, the signal that goes to the oscilloscope is capacitive coupled out (using a 5nF capacity on the signal cable). So the measured rf signal on the oscilloscope has only ~5V peak to peak, but it follows the V_amp shape.

12