Accelerator r d towards erhic
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Accelerator R&D towards eRHIC. Yue Hao, C-AD For the eRHIC Team. eRHIC, linac-ring EIC. Linac=ERL, or the luminosity is negligible The first proposed linac-ring collider 250GeV (p) *15.9 ( e ) @1.5e33 cm-2 s-1 Why linac-ring Luminosity, remove the limitation of b-b parameter of e-beam

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Accelerator R&D towards eRHIC

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Accelerator r d towards erhic

Accelerator R&D towards eRHIC

Yue Hao, C-AD

For the eRHIC Team


Erhic linac ring eic

eRHIC, linac-ring EIC

  • Linac=ERL, or the luminosity is negligible

  • The first proposed linac-ring collider

    • 250GeV (p) *15.9 (e) @1.5e33 cm-2 s-1

  • Why linac-ring

    • Luminosity, remove the limitation of b-b parameter of e-beam

    • High spin polarization (e-beam)

    • Easy to upgrade

    • Easier synchronization with various ion energy.

I. Ben-Zvi, J. Kewisch, J. Murphy and S. Peggs, Accelerator Physics Issues in eRHIC, NIM A463, 94 (2001), C-A/AP/14 (2000).


Erhic layout

eRHIC Layout


Luminosity

Luminosity

Defined by

PSR = 12 MW

Defined by xp = 0.015

Defined by

DQsp = 0.035


Beam synchronization detail

Beam Synchronization, Detail

  • Ion at sub-TeV energies is not ultra-relativistic,Change inenergyvelocityfrequency

  • Linac-ring scheme enable a trick to adjust the frequency of RF to sychronize electron and ion at discrete ion energies

  • Reduces the need of path lengthening.

  • Ring-ring scheme can not take the trick.


Erhic r d efforts

eRHIC R&D efforts

  • IR design, crab cavity and dynamic aperture

  • Beam cooling – major R&D efforts, high priority R&D

  • Polarization and Polarimetry (including electron polarimetry)

  • Polarized 3He production and acceleration

  • Polarized electron source

  • Superconducting RF system

  • Multipass ERL and related beam dynamics

  • FFAG energy recovery pass

  • Linac-ring beam-beam interaction

  • ......


Accelerator r d towards erhic

NS-FFAG Layout of the eRHIC

* 21GeV Design, Jan'14

Arc #2

#1 7.944 GeV

#2 9.266 GeV

#3 10.588 GeV

#4 11.910 GeV

#5 13.232 GeV

#6 14.554 GeV

#7 15.876 GeV

#8 17.198 GeV

#9 18.520 GeV

#10 19.842 GeV

#11 21.164 GeV

7.944 – 15.876 GeV

Injector 0.012 GeV

Linac 1.322 GeV

Arc #1

#1 1.334 GeV

#2 2.565 GeV

#3 3.978 GeV

#4 5.300 GeV

#5 6.622 GeV


Trajectory in ffag

Trajectory in FFAG

2.5819 m

x(mm)

BD=0.1932 T, Gd=-49.515 T/m

Bf= 0.1932 T,

Gf=49.515 T/m

Other half of QF magnet

Bmax[-0.013, 0.4215 T]

Bmax[-0.178, 0.442 T]

21.164 GeV

19.824 GeV

18.520 GeV

17.198 GeV

15.876 GeV

14.554 GeV

13.232 GeV

11.910GeV

10.588GeV

9.266 GeV

7.944 GeV

4.17

5.02

-4.61

-7.5

QF

BD

28.764 cm

28.764 cm

Half of

1.09855 m

Half of

1.09855 m

0.90805 m

θF=3.699017 mrad

θD=3.057567mrad

ρF=296.984m

ρD=296.985 m


Magnet for ffag arcs

Magnet for FFAG arcs


Two alternative magnets

Twoalternativemagnets

PermanentMagnet

Iron(steel)


Accelerator r d towards erhic

  • Bunch-by-Bunch BPM

  • With fewer BPMs than magnets, the space between some FFAG magnets could be used entirely by a BPM; this design produces “stretched” output pulses (from 13 ps rms bunches) intrinsically in the BPM in-vacuum hardware

  • long sampling platforms

  • 1.0 ns

  • 1.18 ns = ½ 422 MHz rf wavelength

  • = minimum FFAG bunch spacing

  • signal processing: use pair of 2 GSPS ADCs

  • triggered ~ 200 ps apart


Multi pass ffag prototype

Multi-pass FFAG Prototype

  • There is on-going plan to build a multi-pass FFAG Energy Recovery Linac prototype to prove the principle and the method of detecting and correcting the beam.

    • Energy of linac ~100MeV

    • # of passes: ~4


Ir design

IR design

Forward detector components

SC magnets

Crab-cavities

p

e


Ir and da

IR and DA

  • 10 mrad crossing angle and crab-crossing

  • 90 degree lattice and beta-beat in adjacent arcs (ATS) to reach beta* of 5 cm

  • Combined function triplet with large aperture for forward collision products and with field-free passage for electron beam

  • Only soft bends of electron beam within 60 m upstream of IP


Beam cooling cec pop

Beam cooling, CEC PoP

  • Traditional stochastic cooling does not have enough bandwidth to cool intense proton beams (~ 3×1011/nsec). Efficiency of traditional electron cooling falls as a high power of hadron’s energy. Coherent Electron Cooling has a potential for high intensity beams including heavy ions.

  • Research Goals:

    • Develop complete package of computer simulation tools for the coherent electron cooling

    • Demonstrate cooling of the ion beam

    • Validate developed model

    • Develop experimental experience with CeC system


Accelerator r d towards erhic

CEC PoP, cont’d

Beam

Dump

Flag

ICT

FEL Section

Helical Wigglers

Flag

Kicker

Section

Modulator

Section

Flag

Linac

Flag

Pepper

Pot

Low Power

Beam Dump

Gun

Bunching

Cavities

ICT


Cec pop anticipated results

CECPoP,anticipatedresults

r.m.s. length of the cooled part 80-120 ps. The cooling effects can be observed with oscilloscope 2 GHz or more bandwidth or spectrum analyzer with similar upper frequency

Electron bunch – 10 psec

Ion bunch – 2 nsec

After 250 sec

After 60 sec

After 650 sec

Modeling of cooling is performed

with betacool by A. Fedotov


Cec timeline

CEC timeline

  • CECPoPRHICrampisdeveloped

  • Injectionsystem(112MHzgun,500MHzbuncher)wereinstalled.

  • Maincavity(704MHz)isfabricated.

  • CommissioninjectorsysteminJuly2014

  • Experimentstarts2015


Polarized e source

Polarized e-source

  • We are aiming at a high-current (50 mA), high-polarization electron gun for eRHIC.

  • The principle we are aiming to prove is funneling multiple independent beams from 20 cathodes.

  • External review was carried out in 2012.

  • Next week, first HV conditioning and possibly first beam!


5 cell srf cavity

5-cell SRF cavity

HOM high-pass filter

  • eRHIC will utilize five-cell 422 MHz cavities, scaled versions of the BNL3 704 MHz cavity developed for high current linac applications.

  • Stability considerations require cavities with highly damped HOMs.

  • The HOM power is estimated at 12 kW per cavity at a beam current of 50 mA and 12 ERL passes.

  • Apply funding to build prototype.

HOM ports

FPC port


Crab cavity

Crab Cavity

  • Development of a highly compact Double Quarter Wave Crab Cavity at 400 MHz.

  • Prototype to be tested in the CERN SPS in 2016- 2017.

Input power waveguides

Cryo jumper

Tuning system

FPC

Helium vessel

Cavity

Magnetic

shielding

Thermal shielding

(80K – nitrogen)


Erl test facility

ERL test facility

  • The BNL ERL objectives 20 MeV at >100 mA (500 mA capability).

  • Experiment in progress, will see first photo-emission soon.

  • Loop in Oct, 2014, project completes in 2016.

All hardware in house, most installed


Electron beam disruption

Ion Beam

Electron beam disruption

e


Summary

Summary

  • There are many on-going simulation and experiment aiming on the challenge port of eRHIC.

  • The design now is based on extensive simulations.

  • R&D experiments are on-going, need few years to finish.


Thank you for your attention

Thank you for your attention!


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