# Presentation: 713392

## Update on the MCTF Scenario(s)

**Update on the MCTF Scenario(s)**

**Y.Alexahin**
**(FNAL)**

## Parameters of Different MC options

**Parameters of Different MC options**

- 			Low Emit.	High Emit.	MCTF07
- s  (TeV)				1.5
- Av. Luminosity (1034/cm2/s) *	2.7	1	1.33-2
- Av. Bending field (T)		10	6	6
- Mean radius (m)		361.4	500	500
- No. of IPs			4	2	2
- Proton Driver Rep Rate (Hz)	65	13	40-60
- Beam-beam parameter/IP	0.052	0.087	0.1
- * (cm)			0.5	1	1
- Bunch length (cm)		0.5	1	1
- No. bunches / beam		10	1	1
- No. muons/bunch (1011)	1	20	11.3
- Norm. Trans. Emit. (m)	2.1	25	12.3
- Energy spread (%)		1	0.1	0.2
- Norm. long. Emit. (m)		0.35	0.07	0.14
- Total RF voltage (GV) at 800MHz	407103c	0.21** 	0.84**
- Muon survival N/N0		0.31 	0.07	0.2
- + in collision / proton		0.047 	0.01	0.03
- 8 GeV proton beam power	3.62*** 	3.2	1.9-2.8
- ---------------------------------------------------------------------------

- *) Luminosity calculated taking account of the hour-glass factor but ignoring the dynamic beta effect.
- **) Momentum compaction in the present ring design c=1.510-4. Note that it would be better to assume f=1.3GHz to keep the RF voltage at a reasonable level (0.52GV for MCTF07 set)
- ***) Assumes  /p ratio of 0.15 after capture and precooling, and only decay losses afterwards. Positive and negative muons are assumed to be produced independently (from different protons).

## Beam loading in the RF structure.

- Short range longitudinal wake per unit length:
- Wmax ~ *q*/(*λσ**)* for a “long” bunch  (*λσ**>a**2*, *a* - aperture).

- σ=1 mm

- σ=2 mm

- σ=4 mm

- σ=8 mm

- For N=2e12, f=1.3 GHz (ILC-like structure) and σ=8 mm Wmax= 6.2 MV/m!

**N.Solyak, V.Yakovlev report @ 03/13/08 MCTF meeting**

## Ongoing effort

**Make High Emittance option more attractive:**
**- magnetically insulated open cell RF for cooling channel **
**- high power p-driver (Project-X linac + MI + coalescing ring, recirculating ILA)**
**- Dielectric Wall Accelerator for strong ******** bunches **
**Reduce emittance to that of MCTF scenario and improve transmission:**
**- faster 6D cooling by using HCC and/or FOFO snake**
**- avoid bunch merging at low energy ( make it at 20-30GeV)**
**- additional cooling using Fernow lattice or PIC (may become possible due to later bunch merging and lower total intensity)**
**- increase reprate to compensate for reduction in peak luminosity (Chuck’s 8GeV p-driver scheme)**

**MCTF Scenario - Y. Alexahin                                          NFMCC meeting, FNAL, March 20, 2008**

**Note: Why cooling in HCC is faster?**
**- HP RF: Emax >50 MV/m @ 800MHz (is there frequency dependence?)**
**- homogeneous optics ******** large DA ******** low p=100MeV/c (not demonstrated yet)**
**- continuous RF (may be unrealizable)**

## Cooling Schemes in HE and MCTF Scenarios

- bunch coalescing

**MCTF Scenario - Y. Alexahin                                          NFMCC meeting, FNAL, March 20, 2008**

**The alternative scheme below should have made (almost) everybody happy: it provided room for various cooling ideas, but...**

## Cooling Schemes in HE and MCTF Scenarios

- bunch coalescing

**MCTF Scenario - Y. Alexahin                                          NFMCC meeting, FNAL, March 20, 2008**

**Bob immediately pointed out that REMEX in 50T solenoids and coalescing at high energy are incompatible (see later)**

**either or**

## FOFO Snake

**800MHz p=100MeV/c case :**
**Cooling by GH****2**** (19% of LH****2****) + LiH wedges**
**Bmax= 9.5T ********  tunes >1  ********  ********c**** > 0**
**Solenoid tilt  ********65mrad ******** Dmax ~ 6cm**
**Emax= 50MV/m**
***Q*****I,II,III**** =1.42+0.005i, 1.51+0.005i, 0.19+0.004i**
**- emittance damping length ~13m**
**Equilibrium ************~0.8mm, ********||****~0.4mm**
**Things to do:**
**   ****Check with ICOOL or G4BL **
**   ****200MHz p=215MeV/c design for initial cooling.  Estimated performance:**
**********, ********|| ****~ 2cm ******** 5mm in 140m (10% decay loss)**
**   ****Tilt 2****nd**** and 4****th**** solenoids horizontally (and displace all solenoids from axis) to make a helix. **
**Hopefully ********c**** will become large enough to discard LiH wedges ******** smaller emittances **

**MCTF Scenario - Y. Alexahin                                          NFMCC meeting, FNAL, March 20, 2008**

## R.Palmer @ 12/14/06 MCTF meeting

**R.Palmer @ 12/14/06 MCTF meeting**

## Possible Benefit from R. Fernow’s Lattice 

**According to Bob, he abandoned the idea of the ****New Ring**** employing one of Rick’s lattices due to strong Space Charge effects. Will a 10-fold reduction in intensity help?**
**Starting with much lower transverse emittance, will it be possible to cool it down to ~10 ********m without excessive longitudinal blowup in 50T solenoids?**

**MCTF Scenario - Y. Alexahin                                          NFMCC meeting, FNAL, March 20, 2008**

## R.Palmer @ MCD Workshop, BNL Dec. 2007

**R.Palmer @ MCD Workshop, BNL Dec. 2007**

## R.Palmer @ MCD Workshop, BNL Dec. 2007

**R.Palmer @ MCD Workshop, BNL Dec. 2007**

## Analytical Study of R. Fernow’s Lattice with SC

**Bob showed that emittances ************N**** ~10********m**** are feasible, is the space charge really an obstacle?**

**z (cm)**

**MCTF Scenario - Y. Alexahin                                          NFMCC meeting, FNAL, March 20, 2008**

********** ****(cm)**

**Bmax=17T with p=100MeV/c,**
**Emax=****40MV/m**** @ 800 MHz**
**Q********=1.4+0.0044i, QL=0.135- 0.004i, **
****** ****5.4% transverse emittance reduction per cell (0.8m)**

********** ****(min) = 0.76cm  ******
****** ********N= ****44********m ****(equilibrium)**

## Analytical Study of R. Fernow’s Lattice with SC

**MCTF Scenario - Y. Alexahin                                          NFMCC meeting, FNAL, March 20, 2008**

**|********Q_SC|**

****** ****@ absorber (cm)**

**Q****I,II**

**|********Q_SC|  (linear SC parameter)**

**The range of linear stability is amazingly large, for cited emittances it corresponds to **
**Nmu=2.5e12**
**It looks like the lattice can accept the full intensity bunch of the high-emittance option!**

**The “dynamic beta” effect – well known in collider theory – facilitates the cooling!**
**Can it be employed to obtain smaller emittances?**

## Two Scenarios with Fernow’s Lattice

**Original R.Palmer’s idea:**
**201/402 MHz 6D cooling ******** bunch merging****	******** 201/402/804 MHz 6D cooling ******** **
**804 MHz Fernow ********  REMEX in 50T solenoids ******** acceleration**
**with REMEX in Fernow’s lattice:**
**201/402/804/1608 MHz 6D cooling ******** Fernow 6D cooling ******** **
**REMEX in 1608 MHz Fernow ********  acceleration ******** bunch merging @ 30GeV**
**Parameters of 1.6 GHz Fernow REMEX channel:**
**p=50MeV/c, L=0.2m, Bmax=34T ******** **
**equilibrium**** ******** ********N < 10********m**** **

**MCTF Scenario - Y. Alexahin                                          NFMCC meeting, FNAL, March 20, 2008**