1. DODGE: Direct Observations in DESIREE of Gear-changing Events
A first demonstration of asymmetric harmonic number beam-beam interactions
Speaker: Edith Nissen

2. Is there anything I’m missing in this experiment design?
Outline of the project
Provide a demonstration of a gear-changing system using the Double Electrostatic Ion Ring ExpEriment (DESIREE) in Stockholm Sweden.
Most likely take place in spring of 2020 (contingent on their approval)
There is a possibility this will be in the fall (That’s why we’re doing this now)
Is there anything I’m missing in this experiment design?

3. Gear Changing and JLEIC
During low energy operations at JLEIC, the velocities of the electrons and ions will not match.
Allowing for different harmonic numbers in each ring would take advantage of this to keep the collisions synchronized.
First treated theoretically for possible use in RHIC.
This scheme would reduce systematic error, but could lead to destructive resonances. The JLEIC project has an effort under way to create a high-fidelity modeling package for this effect. 3 4 2 1 a b c

4. DESIREE Background Dual Electro-Static Ion Ring ExpEriment
Located at the University of Stockholm, in Sweden.
Up to 25 keV on up to 100 keV singly, oppositely-charged, ions.
Currently matches velocities to study neutralization reactions in the interstellar medium.
A part of the Swedish national infrastructure, eager for outside users.

5. More DESIREE Background
The diagnostics for our purposes will be 2 pickups (BPMS) and a neutral particle detector downstream of the merger region.

6. Overall Strategy
The main problem is that DESIREE wasn’t designed to do this sort of thing.
Our main obstacle is signal to noise ratio, so much of the program will be to calibrate our diagnostics and beam parameters to get a good signal, without inadvertently amplifying noise that we think is signal.
RF is difficult, and isn’t used very often. It has been known to reduce lifetimes significantly.
This experiment will use a 4 on 3 using 7.5 keV C- and 15 keV N+ respectively.
If gear changing is being maintained the overall pickup signal should look something like this:
Voltage
Time

7. Step 1: Each beam separately
Each beam will be tested in its own ring separately without collisions.
Use this to characterize the signals and controllability of each beam.
Help determine lifetime of the beam; this will determine how long we can try to perform the gear changing experiment.

8. Step 2: Gear changing with empty buckets
The best way to measure this effect is using the offsets between the beam signals on the pickups, when the beams are colliding symmetrically through the merging region there will be a symmetric pattern on the readout from the pickups. This method will use a combination of empty and filled buckets to, at a glance, show the background (no collision), collisions, and beams passing through without a collision.
0 = empty, * = Bunch
3 bunch * * * * * * * *
4 bunch * * * * * *

9. Step 3: Gear Changing with full buckets
This is exactly what it says
One possibility is to alter the bunch charge one bunch in a train (one being lower than the rest is apparently the easiest)
L = Lower Charge, * =Normal Bunch
3 bunch L * * L * * L * * L * *
4 bunch L * * * L * * * L * * *

10. Step 4?: If there’s time
Increase the number of bunches, and try for n(n-2)
Anything else that needs to be attempted?
Anything I’m missing?

11. Thank You For Your Attention