## Internal Review of the BBC Project, FNAL, June 4, 2001

## *Vladimir Shiltsev*

## [Tevatron Beam Studies with Electron Beam]{.underline}

## 

## [p-tuneshift:]{.underline} vs timing

## maximum vs e-current

## dQ=+0.007 vs e-energy (U~cathode~)

## at 980 GeV vs e-beam size 

##  vs proton energy 

##  vs steering (BPMs, dQ, p-orbit)

## 

## [p-lifetime:]{.underline} vs steering 

## the best is vs Tev working point 

## 24 hours at vs e-current

## dQ=(4-6)e-3 vs e-beam stability (PSs, ions)

##  vs e-beam/p-beam size

##  at large separation

## 

## [next studies:]{.underline} e-size/shape effects on dQ and τ/losses 

##  emittance growth vs stabilization

##  effects of ions if any

##  antiproton-electron collisions 

## 

## *ultimate goal of the studies is to achieve the same or better beam lifetime with TEL at about the same dQ as in TeV and around typical working points (i.e., we'll compete with the Tev group/MCR... rather than with the Recycler team).* 

## 

## [problems/needed improvements (in order of urgency):]{.underline} 

## better steering: better BPMs, p-orbit tickling system

## p-diagnostics: (fly-wire?,IPMs,SyncLight), auto-dQ better e-beam: wider/smoother beam (10A, 30kV gun) current/position stabilization 

##  

## [Conclusion:]{.underline} "proof-of-principle" stage for the TEL is over,

##  it's time for "proof-of-principle" for the BBC,

## there are no show-stoppers yet, we know what we have to do on each of the problems 

## 

## [To keep the pace, we are asking for:]{.underline} 

## 

## [TIME]{.underline} 20 shifts at the rate ∼3/month

##  - end of store OK if \>1 hr and acceptable ε

## [MONEY]{.underline} 230K\$ to built the 2^nd^ TEL magnets

##  - 80K\$ FY'01, will take 1 year to built

## [PEOPLE]{.underline} 2 postdocs (experiment+theory) 

## to "½ -fill" places of Solyak and Alexahin 

p-tune shifts by TEL: 150GeV, 980 GeV

> ![](media/image1.wmf)

**Protons instead of pbars: what's the difference for TEL?**

**Tuneshift formula:**

$$\text{dQ}_{x,y} = \mp \frac{\beta_{x,y}}{2\pi} \cdot \frac{1 \pm \beta_{e}}{\beta_{e}} \cdot \frac{J_{e}L_{e}r_{p}}{e \cdot c \cdot a_{e}^{2} \cdot \gamma_{p}}$$

**Consider 10 kV e-beam  β~e~** **=0.2**

### For protons (co-moving) 1- β~e~=0.8 ; for pbars (collide) 1+β ~e~ =1.2

### 

### Therefore, we expect that for pbars the tuneshift will be 1.2/0.8=1.5 times the protons dQ, e.g.,

### [+0.067 for protons equivalent to - 0.01 for antiprotons]{.underline}

## [lifetime can be good if e-beam is steered well:]{.underline} 

τ~p~=22.5hrs, dQ~x~=0.0051, Q~x,y~=0.562/0.556, ε~x,y~=20/30, J~e~=2 A,
U~e~=6kV

> ![](media/image2.png){width="7.877083333333333in"
> height="6.595138888888889in"}

## [e-beam missteering leads to high p-losses :]{.underline}

τ~p~=1.5hrs, dQ~x~≈0.002, Q~x,y~=0.583/0.576, ε~x,y~=27/32, J~e~=1.1 A,
U~e~=6kV

> ![](media/image3.png){width="7.492361111111111in"
> height="6.272222222222222in"}

## [no p-losses if e-beam is 5 mm away:]{.underline}

τ~p~=90hrs, [dQ~x~=-0.0003]{.underline}, Q~x,y~=0.562/0.556,
ε~x,y~=40/50, J~e~=2.2 A, U~e~=6kV

> ![](media/image4.png){width="7.741666666666666in"
> height="6.481944444444444in"}

## There is no formula for beam lifetime, but 

## what theory says what we observe

## 

## better lifetime if e-p beams centered true

## 

## lifetime depends on working point (probably) true

## 

## better lifetime at smaller e-current there are indications of that

## 

## very good lifetime if 10σ separation true

## 

## more stable e-beam  better lifetime there is indication of that

## 

## wider e-beam w.r.t. protons  better τ there are indications of that 

## 

## smoother edges of e-profile  better τ not studied yet

## [2A e-pulse (yellow) and e,p-bunches seen byBPM:]{.underline}

RF Tube based HV modulator dU~anode~=6kV, 800ns, J~e~=1.95 A, U~e~=6kV

> ![](media/image5.png){width="8.366666666666667in" height="6.275in"}

## [100 ns e-pulse seen by new BPM (A, B, A-B):]{.underline}

FID pulser dU~anode~=12kV, 100ns, J~e~≈3 A, U~e~=10kV

![](media/image6.png){width="8.366666666666667in" height="6.275in"}

## [Recently, RMA connectors installed for BPM cables:]{.underline}

...that maintained 50 Ohms all along and reduced "ringing" significantly

> ![](media/image7.jpeg){width="8.74236111111111in" height="6.55625in"}

## [p-orbit tickling by TEL:]{.underline}

Kick ∼4πdQ a/β~1~  Orbit change ∼(β~1~β~2~)^2^/2sin(πQ)cos(ψ)×Kick

Estimated dOrbit ∼ 1μm

[Measured p-orbit tickling by TEL:]{.underline}

> ![](media/image8.wmf){width="8.609027777777778in" height="6.8in"}

[Horizontal tuneshift: theory and experiment]{.underline}
![](media/image9.wmf){width="8.49236111111111in"
height="6.395833333333333in"}

**Uncertainties: β~X~ ± 5%, β~e~ ± 5%, J~e~ ± 5%, L~e~ ± 10%, a~e~^2^ ±
10%**

dQ∝1/β~e~=1/√U~e~

> ![](media/image10.wmf){width="8.36736111111111in"
> height="6.411111111111111in"}

#### Ions help us

> ![](media/image11.wmf){width="7.865277777777778in"
> height="6.675694444444445in"}

Flying wire is not very accurate:

6 consecutive measurements (4/21/01, 2:22 a.m., e-beam OFF)

ε~Vertical~ ε~Horizontal~

5.  22.4

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9.  27.0

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5.  19.3

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4.  26.8

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5.  21.1

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9.  26.1

mean 33.8 23.8

rms 0.64 3.3