# Presentation: 562998

## Facility Strategy

- RHIC performance overview
- Luminosity and polarization evolution
- 	(towards “enhanced luminosity”)
- Future upgrades
-      EBIS
-      RHIC luminosity upgrade
-      eRHIC

## Gold Ion Collisions in RHIC

**RHIC**

**AGS**

**BOOSTER**

**9 GeV/u**
**Q = +79**

**1 MeV/u**
**Q = +32**

**Beam Energy = 100 GeV/u **

## RHIC Au-Au performance – 2 x design luminosity

**Injector**

**RHIC**

- design luminosity

**Luminosity [x10****26****]**

**0**

**5**

**10**

**15**

## RHIC Run 5 Delivered Cu-Cu Luminosity

**RHIC Run 5 Delivered Cu-Cu Luminosity**

## RHIC polarized proton accelerator complex

_***BRAHMS***_

_***STAR***_

_***PHENIX***_

**AGS**

**LINAC**

**BOOSTER**

- Pol. H- Source

- Spin Rotators
- (longitudinal polarization)

- Solenoid Partial Siberian Snake

- Siberian Snakes

- 200 MeV Polarimeter

- AGS Internal Polarimeter

- Rf Dipole

- RHIC pC Polarimeters

- Absolute Polarimeter (H jet)

- AGS pC Polarimeters

**Strong Helical AGS Snake**

- Helical Partial Siberian Snake

_***PHOBOS***_

- Spin Rotators
- (longitudinal polarization)

- Spin flipper

- Siberian Snakes

## New AGS helical snakes

**New AGS helical snakes**

- 2.6 m

- 2.6 m

- 30% s.c. helical snake build at BNL SMD
- Installed in March 2005

- Warm snake avoids polarization mismatch at AGS injection and extraction.
- Cold strong snake eliminates all depolarizing resonances in AGS.

- 5 % helical snake build at Tokana Industries funded by RIKEN.

## Siberian Snake in RHIC Tunnel

- Siberian Snake: 4 superconducting helical dipoles, 4Tesla, 2.4 m long with full  360 twist

- Funded by RIKEN, Japan
- Designed and constructed at BNL

## Polarization survival in RHIC

- Spin rotator ramp

- Acceleration and squeeze ramp

## RHIC – a Uniquely Flexible High Luminosity Collider

- (Nucleon-pair luminosity *A*1*A*2*L* allows comparison of different species)

- Luminosity increased by 2 orders of magnitude in 4 years.

## RHIC Accelerator Complex Operations

**7 major accelerator systems (2 Tandems, Linac, Booster, AGS, 2 RHIC rings) consisting of:**
- 6 miles of evacuated beam lines (large part of it below 10-10 Torr)
- 4.5 miles of superconducting magnets and cryostat
- 25 kW@4.5K He refrigerator (12 turbines, 25 compressors,...)
- 2 rapid cycling synchrotrons (16 MW and  40 MW power supplies)
- 42 high power rf systems (0.1 – 200 MHz)
- 1300 programmable DC power supplies
- 54 pulsed power systems
- FY05 operations budget ($95M, equal to the recommendation of $95M [2005$] from 2002 RHIC operations review) is sufficient for safe and efficient operation of 31 cryo-weeks with excellent availability.
- Ongoing investment to improve operating efficiency (cryo upgrade: 2 MW reduction of el. power consumption, EBIS)

## RHIC availability and time in store

**RHIC availability and time in store**

- Excellent availability despite     very complex operation modes.
- Machine set-up time reduced to just 3 weeks.

**FY05Q2 Weekly Availability**

## Major contributions from non-DOE sources to the RHIC accelerator complex:

RIKEN, Japan: RHIC Spin (~ $70M, RBRC)

NASA: NASA Space Radiation Laboratory ($4.5M contribution to EBIS)

NSF and Canada: RSVP (construction not started yet, major infrastructure upgrade to Booster and AGS)

- RIKEN, Japan: RHIC Spin (~ $70M, RBRC)
- NASA: NASA Space Radiation Laboratory ($4.5M contribution to EBIS)
- NSF and Canada: RSVP (construction not started yet, major infrastructure upgrade to Booster and AGS)

**Connection to other programs**

## Future plans for RHIC

- Machine goals for next few years with upgrades in progress:
**Enhanced RHIC luminosity (112 bunches, ********* = 1m):**
**Au ****– ****Au: ****	****    8 ******** 10****26**** cm****-2**** s****-1 ****(100 GeV/nucleon) **
**For protons also 2 ******** 10****11**** protons/bunch (no IBS):**
**p******** – p********: ****	****  60 ******** 10****30**** cm****-2**** s****-1****; 70 % polarization (100 GeV)****	****150 ******** 10****30**** cm****-2**** s****-1****; 70 % polarization (250 GeV)**(luminosity averaged over store delivered to 2 IRs)
- EBIS (low maintenance linac-based pre-injector; all species incl. U and pol. He3; avoid Tandem investment; ~ 3 year pay-back period)
- RHIC luminosity upgrade (e-cooling, ~10 **** more luminosity, R&D in progress)
- eRHIC (high luminosity (1  1033 cm-2 s-1) eA and pol. ep collider)

- 2 achieved

- 6 achieved

## EBIS/Linac-based RHIC Pre-Injector

- Highly successful development of Electron Beam Ion Source (EBIS) at BNL: meets RHIC performance requirements.
- EBIS allows for a reliable, low maintenance Linac-based pre-injector replacing the Tandem Van de Graaffs
- Greatly reduced operating costs, and avoidance of ~ 9 M$ in reliability-driven investments in the tandems
- Highly flexible to handle the multiple simultaneous needs of RHIC and NSRL
- Produces beams of ALL ion species including noble gas ions (NSRL), Uranium (RHIC) and polarized He3 (eRHIC)
- Ready to start construction, CD0 received; Cost: 19.4 M$; 3.5 year construction schedule: FY2006 – 09NASA participation  ($ 4.5M)

## EBIS layout

## RHIC luminosity upgrade

- Eliminate beam blow-up from intra-beam scattering with  electron beam cooling at full energy!
- What will remain the same:
- 120 bunch pattern
- 100 ns collision spacing ( ~ same data acquisition system)
- Only one beam collision between DX magnets
- 20 m magnet-free space for detectors
- No “mini-beta” quadrupoles
- Approx. the same bunch intensity
- No new beam intensity issues
- Background similar as before upgrade
- What changes:
- Smaller transverse and longitudinal emittance
- Smaller vertex region (Increased luminosity within detector acceptance)
- Beta squeeze during store to level luminosity
- Store length is limited to ~ 5 hours by “burn-off” due to Au-Au interactions (~ 200 b)

## Electron Cooling R&D

- Superconducting ERL

**Electron Cooling R&D**

- Buncher Cavity

- Cooling Solenoids (2 x 13m, 2-5 T)

- Debuncher Cavity

**Gold beam**

- Benchmarking of IBS and cooling simulation codes
- Demonstrate high precision (<10 ppm) solenoid (2-5 T)
- Demonstrate 20 nC, 100-200 mA 703.8 MHz CW SCRF electron gun
- Develop 703.8 MHz CW superconducting cavity for high intensity beams
- Build R&D Energy Recovering Linac (ERL)

- 54 MeV, 100 mAelectron beam

## RHIC Luminosity with and without Cooling

**RHIC Luminosity with and without Cooling**

- With e-cooling
- Without e-cooling

- Luminosity leveling through
- continuously adjusted cooling
- Store length limited to 4 hours by “burn-off”
- Four IRs with two at high luminosity

- 2 mm

- 5 hours

**Electron cooling simulations**

- Transverse beam profile during store
- Also able to pre-cool polarized protons at injection energy

## RHIC Luminosity Upgrade with Electron Cooling

**Gold collisions (100 GeV/n x 100 GeV/n): ****	**** w/o e-cooling****	****with e-cooling**
- Emittance (95%) m	15  40 	15  3
- Beta function at IR [m]	1.0	1.0  0.5
- Number of bunches	112	112
- Bunch population [109]	1	1  0.3
- Beam-beam parameter per IR	0.0016	0.004
- Ave. store luminosity [1026 cm-2 s-1]	8	70
**Pol. Proton Collision (250 GeV x 250 GeV):**
- Emittance (95%) m	20	12
- Beta function at IR [m]	1.0	0.5
- Number of bunches	112	112
- Bunch population [1011]	2	2
- Beam-beam parameter per IR	0.007	0.012 ?
- Ave. store luminosity [1032 cm-2 s-1]	1.5	5.0

## Electron-Ion Collider at RHIC: eRHIC

**Electron-Ion Collider at RHIC: eRHIC**

- 10 GeV, 0.5 A e-ring with 1/3 of RHIC circumference (similar to PEP II HER)
- 10 GeV electron beam  s1/2 for e-A :  63 GeV/u;    s1/2 for e-p: 100 GeV
- Electron cooling required for high luminosity e-A and low energy e-p collisions
- Polarized e-He3 (e-n) collisions with EBIS
- Existing RHIC interaction region allows for typical asymmetric detector
- Luminosity: up to 1  1033 cm2s1 per nucleon (1  1034 cm2s1 with linac – ring scheme)

- BNL, MITcollaboration

## Summary

- Since 2000 RHIC has collided, for the first time,
- Heavy ions
- Light on heavy ions
- Polarized protons (45% beam polarization)
- Heavy ion luminosity increased by factor 100
- For next 4 years planned:
- Factor 2 increase in heavy ion luminosity
- Factor 6 increase in proton luminosity
- Factor 2 increase in proton beam polarization
- Future upgrades:
- RHIC luminosity upgrade (~10x) using electron cooling at store
- Electron-ion collider eRHIC

## Back-up material

## RHIC design, achieved and enhanced design parameters                                                                     

| Mode | No ofbunches | Ions/bunch [9]  | *[m]  | Beampolarization |  | Lpeak[cm-2s-1] | Lstore ave[cm-2s-1]  | A1A2Lstore ave[cm-2s-1] |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Design values (1999) |  |  |  |  |  |  |  |  |  |
| Au – Au | 56 | 1.0 | 2 |  |  | 81026  | 21026  |  | 81030  |
| p – p  | 56 | 100 | 2 |  |  | 51030  | 41030  |  | 41030  |
| Achieved values (2004) |  |  |  |  |  |  |  |  |  |
| Au – Au | 45 | 1.1 | 1 |  |  | 151026  | 41026  |  | 161030  |
| p – p  | 56 | 70 | 1 |  | 45% | 51030  | 41030  |  | 41030  |
| p – p  | 56 | 170 | 1 |  |  | 151030  | 101030  |  | 101030  |
| Enhance design values (2008) |  |  |  |  |  |  |  |  |  |
| Au – Au | 112 | 1.1 | 1 |  |  | 301026  | 81026  |  | 311030  |
| p – p  | 112 | 200 | 1 |  | 70% | 801030  | 651030  |  | 651030  |

**Other high luminosity hadron colliders:**
- 	achieved 	goal	scaled to 200 GeV
- Tevatron (2 TeV)	1001030 	    2001030 	  201030
- LHC (14 TeV)	 	100001030 	1401030

## Alternative eRHIC Design: Linac - Ring

- Electron ring replaced by energy-recovering linac, electrons in RHIC arcs:Higher luminosity (1  1034 cm2s1), simpler IR design, multiple IRs possible, 20 GeV upgrade possible

## EBIS Completion

**EBIS Completion**

## FY06 cryo-weeks reduced from 31 to 12 weeks
Combine FY06-07 runs for some models. Avoid summer running. Begin on 10/1/06 after 15 month shutdown.
$300K (ions) - $325K (polarized proton) / week running and $75K / week power costs when off
EBIS construction is expedited. Funding increased from $2.0M to $3.6M (+ $1.5M from NASA). Reprogram AIP ($0.5M), capital ($0.7M + $0.4M)
Operations manpower reductions of 30-34 FTE (355->325-321 FTE)
The efficient and safe operation of the accelerator complex with the proposed staff size is more difficult. Present staff workload and stress levels are high. Concern that key accelerator physicists will move across the Atlantic. Loss of expertise is a major issue.
Some staff would be assigned to RSVP, if funding arrives in time.
Electron cooling R&D will be reduced as EBIS takes priority and RHICII recedes into future
Reassign waste management funding. 50% used to support FY06

- Combine FY06-07 runs for some models. Avoid summer running. Begin on 10/1/06 after 15 month shutdown.
- $300K (ions) - $325K (polarized proton) / week running and $75K / week power costs when off
- EBIS construction is expedited. Funding increased from $2.0M to $3.6M (+ $1.5M from NASA). Reprogram AIP ($0.5M), capital ($0.7M + $0.4M)
- Operations manpower reductions of 30-34 FTE (355->325-321 FTE)
- The efficient and safe operation of the accelerator complex with the proposed staff size is more difficult. _Present_ staff workload and stress levels are high. Concern that key accelerator physicists will move across the Atlantic. Loss of expertise is a major issue.
- Some staff would be assigned to RSVP, if funding arrives in time.
- Electron cooling R&D will be reduced as EBIS takes priority and RHICII recedes into future
- Reassign waste management funding. 50% used to support FY06

**Impact of FY2006 Presidential on Accel. Ops.**

## Impact of FY06P + constant effort (flat) funding on Accel. Ops.

- Combined FY06-07 run.
- With EBIS:
- Reprogram funds to complete EBIS project (FY06-09).
- No run in FY08
- Combined FY09-10 run.
- Yearly 24 cryo-weeks running FY11 and later. Reduced operations cost form EBIS completion allows for more running.
- Without EBIS:
- Reprogram funds to complete Tandem reliability upgrade (FY07-09)
- Combined FY08-08 run
- Yearly 20 cryo-weeks running FY10 and later
- The efficient and safe operation of the accelerator complex with the staff size is more difficult.
- This funding model supports the most favorable but still a dwindling long term physics program

## Impact of FY06P + “flat-flat” on Accel. Ops.

- EBIS will not be built.
- Flat-flat funding would only allow for a combined FY06-07 and a combined FY08-09 run and then unable to support a physics program thereafter.
- Loss of expertise to complete the proposed runs is significant.
- The efficient and safe operation of the accelerator complex with the FY06 staff size is more difficult.
- This funding model rapidly leads to RHIC termination.

## BNL proposed (FY2005 + constant effort)

- 31 cryo-week each year
- Physics program includes ions and polarized protons to 500 GeV cm.
- EBIS project completed in 3.5 years
- Reduce injector group manpower
- Accelerator R&D support of electron cooling for future RHICII and eRHIC would remain on a fast track.
- AIP support to continue to replace aging machine components and improve performance, eg. RHIC cryogenic system is 25 years old, would be accomplished in an orderly manner.
- RHIC running efficiency and safety are not a concern.