# Presentation: 367776

## AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

**Kevin A. Brown**
**C-AD**
**kbrown@bnl.gov**

## Booster and AGS ModificationsContents

**Introduction: RSVP Basic Requirements**
**Booster Parameters and Performance**
**AGS Parameters and Performance**
**Overview of Basic Areas Requiring Improvements**
**Requirements**
**Environment and Safety Modifications**
**Basic Infrastructure Modifications**
**Booster Modifications**
**AGS Modifications**
**Slow Extraction and Switchyard Modifications**
**Summary**
** ****Supplemental Material **

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Introduction: RSVP Basic Requirements

|  | Normal SEB | KOPIO | MECO |
| --- | --- | --- | --- |
| P  (GeV/c) | 25.5 | 25.5 | 7.5 |
| Rep. Time (sec) | 5.3 | 5.3 | 1 |
| Spill Length (sec) | 3 | 3 | 0.5  |
| Intensity | > 70 TP/pulse | 100 TP/pulse | 40 TP/pulse, 
2 bunches |
| Bunch lengths & spacing | DC | 200 psec 
40 nsec | ~10 nsec 
1.35 usec |
| p/p (%) | 0.7 - 0.9 | < 0.5 | ~ 1.0 |
| Integrated Intensity*
(# protons) | 6.3x1020
(post-Booster) | 9x1020 | 4x1020 |
| Extinction | NA | 10-3 | 10-9 |

- * Normal SEB value Includes non-SEB proton operations.

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Booster Parameters and Performance

| Parameter | Value |
| --- | --- |
| Circumference | 201.78 (1/4 AGS) m |
| Ave. Radius | 32.114  m |
| Magnetic Bend R | 13.8656 m |
| Lattice Type | Separated Function, FODO |
| No. Superperiods | 6 |
| No. of Cells | 24 |
| Betatron Tunes,X,Y | 4.82, 4.83 |
| Vacuum Chamber | 70 x 152 mm Dipoles
152 mm (circular) Quads |
| Max. Rigidity | 17 Tm |
| Injection Rigidity | 2.2 Tm 
(200 MeV protons) |
| Acceleration Rate | 8.9 T/s  (7.5 Hz) |

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## AGS Parameters and Performance

**AGS Parameters and Performance**

| Parameter | Value |
| --- | --- |
| Circumference | 807.091 m |
| Ave. Radius | 128.453  m |
| Magnetic Bend R | 85.3785 m |
| Lattice Type | Combined Function, FODO |
| No. Superperiods | 12 |
| Betatron Tunes,X,Y | 8.72, 8.80 |
| Vacuum Chamber | 78 x 173 mm Dipoles |
| Max. Rigidity | 110 Tm |
| Injection Rigidity | 9.076 Tm 
(1.94 MeV protons) |
| Acceleration Rate (max) | 2.5 T/s |

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Booster & AGS Performance

**Imposed limits to lost beam power to maintain hands-on maintenance (ALARA).**
**AGS SEB operation, 5.4 s AGS cycle time, 6 Booster cycles.**
**Achieved ****19.6 Tp/sec, Booster Late**** & ****13.7 Tp/second, AGS Late. **
**Table 2: SEB 10 Pulse Ave. Data (best performance)**

|  | Intensity
(Tp/cycle)* | Efficiency
 (%) | Beam Loss
(Tp/cycle) | ALARA
(Tp/cycle) | Loss 
(kW) | Loss/m
(W/m) |
| --- | --- | --- | --- | --- | --- | --- |
| Linac | 177 | - | - | - | - |  |
| Booster Injected | 125 | 71 | 52 | 54 | 0.31 | 1.5 |
| Booster Extracted | 106 | 86 | 18 | 18 | 0.5 | 2.5 |
| AGS Injected | 78 | 74 | 28 | 31.5 | 1.62 | 2.0** |
| Transition | 76 | 98 | 2 | 3 | 0.26 | 0.3 |
| After Transition | 73 | 95 | 3 | 4.5 | 0.63 | 0.8 |
| AGS Late | 73 | 100 | 0 | 1.5 | 0 | 0 |

- * 1 Tp = 1x1012  protons

- ** assumed lost in AGS

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Booster & AGS Performance

**Imposed limits to lost beam power to maintain hands-on maintenance (ALARA).**
**AGS FEB operation, 2.77 s cycle AGS cycle time, 6 Booster cycles**
**Achieved ****30 Tp/sec, Booster Late**** & ****22 Tp/sec, AGS Late**
**Table 3: FEB 10 Pulse Ave. Data (best performance, not sustainable operation)**

|  | Intensity
(Tp/cycle) | Efficiency
 (%) | Beam Loss
(Tp/cycle) | ALARA
(Tp/cycle) | Loss 
(kW) | Loss/m
(W/m) |
| --- | --- | --- | --- | --- | --- | --- |
| Linac | 115 | - | - | - | - | - |
| Booster Injected | 89 | 77 | 27 | 27.7 | 0.31 | 1.5 |
| Booster Extracted | 83 | 93 | 6 | 9.2 | 0.33 | 1.6 |
| AGS Injected | 66 | 78 | 18 | 16.3 | 2.0 | 2.5** |
| Before Transition | 62.3 | 94 | 3.7 | 1.5 | 0.9 | 1.1 |
| After Transition | 61.6 | 99 | 0.6 | 2.3 | 0.2 | 0.2 |
| AGS Late | 61.4 | 99.5 | 0.3 | 0.8 | 0.25 | 0.3 |

- ** assumed lost in AGS

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Overview of Basic Areas Requiring Improvements

**Categories of Improvements and Modifications**
** ****Ensure RSVP has no impact on RHIC and NASA operations**
** ****Minimize occupational dose received by workers**
** ****Minimize environmental impact of RSVP operations**
** ****Reduce the risk of equipment failure**
** ****Reduce the risk of fire or electrocution**
** ****Achieve RSVP Intensity/Throughput goals**
** ****RSVP Modifications**
**General Areas of Improvements and Modifications**
** ****Ground water protection by capping soil-shielding over tunnels**
** ****Cables and Cable trays**
** ****Radiation damaged magnet coils**
** ****Obsolete Controls**
** ****Aging and radiation damaged equipment and instrumentation**
** ****Upgrades to achieve intensity goals**
** ****Modifications for RSVP (bunched beam slow extraction)**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Requirements

**Accelerators must not be activated beyond what is maintainable by people (as low as reasonably achievable {ALARA}) **
**Booster**
** ****ions to the NASA Space Radiation Laboratory (NSRL****)**
** ****ions to the AGS**** **
** ****polarized protons to the AGS**** **
** ****high intensity protons to the AGS**** **
**AGS**
** ****ions to RHIC**** **
** ****ions to NASA**
** ****polarized protons to RHIC**** **
** ****high intensity protons to RSVP**** **
**Switchyard**
** ****high intensity protons to RSVP **
** ****ions to a high energy NASA Space Radiation facility **

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Environment and Safety Modifications

** ****Soil-Shielding will be covered by water impervious caps **
**groundwater activation <  5 % of the EPA drinking water limit**
-  High intensity protons produce significant prompt radiation
-  beam loss required to exceed the 5 % level is not detectable
**Cable repaired and replaced.**
** ****Cables must not pose fire or electrocution hazards**
** ****Magnet coil replacements, new magnets, upgrade to kicker P.S.’s**
** ****radiation burden to workers must be kept ALARA**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Shield Caps: Existing

- Liner Cover over NSRL.

- Concrete/Soil mix over area’s of AGS tunnel.

- Existing Concrete Shield Cap

- Area’s to be covered with Concrete, outside RSVP project

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Concrete Shield Caps

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Basic Infrastructure Modifications

** ****Electrical Modifications**
** ****Cable repairs and replacement**
** ****upgrade of kicker Pulse Forming Network’s (PFN)**
** ****Purchase 6 sets of Booster dipole magnet coils, repair one magnet**
** ****Replace 8 sets of magnet coils around AGS extraction septa magnets**
**Mechanical Modifications**
** ****Build a spare Booster extraction septum magnet**
** ****AGS RC networks upgrade for high current beams**
** ****Instrumentation**
** ****Upgrade & repair loss monitor systems**
** ****High beam current wall monitors**
** ****remote gain control on Booster To AGS instrumentation**
** ****repair and upgrade AGS ring grounds monitor systems**
**Controls**
** ****replace obsolete hardware and support modifications**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Booster Modifications

** ****Booster Injection**
** ****C5 and C7 magnet coil failures**
** ****Collimation system**
** ****Reduce activation of components by concentrating losses on dump**
** ****Fast RF Feedback**
** ****greater stability and improved beam loading compensation for High Intensity**
** ****Heavy Ion Inflector Protection**
** ****Prevent damage to inflector from High Intensity Protons**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Booster Injection

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Booster Injection

**Reducing the risk of a C7 magnet failure**
** ****Thicker H- stripping foil. Will reduce H****0**** to less than 0.3 %**
-  200 gm = 0.3 %
-  250 gm = 0.15 %
-  Main Issue is emittance growth
** ****Add Carbon Block absorber in Quad Upstream of C7, located to catch H****0**
-  Main Issue is does this significantly reduce acceptance?
**Reducing the risk of a C5 magnet failure**
** ****Restrict acceptance of transfer line, to prevent beam scraping at entrance to C5  (collimation in transfer line)**
-  assumes cause is beam scraping at or near the entrance
** ****Add Carbon Block between vacuum chamber and coils on inside of C5 magnet, to diffuse and absorb lost particles.**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## C3 Inflector Protection

**Inflector septum distortion. Should be perfectly flat.  Presumed cause is high intensity protons scraping on the septum.**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Collimation

** ****Goal is to allow higher throughput by concentrating losses in one well controlled area, permitting ALARA limits to be raised.**

- FNAL, from AAC report, May 2004

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Fast RF Feedback

**Line density from wall current monitor.**
**h=1+2,  RF capture at injection.  4 turns per sweep.**

**RF gap volts sum.  1****st**** and 2****nd**** harmonic cavities at injection during RF capture.**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## AGS Modifications

**Active Filter ****	****	****	****– spill structure**
**Thin Septum Power Supply**
**Thick Septum Power Supply**
**Dump Bump Power Supply  ****	****– spill structure**
**New Extraction Septa****	****- acceptance of extraction channel  **
**Sextupole Coils**
**Collimators**
**Impedance reduction**
**Motion systems upgrades****	****- damaged and obsolete**
**Video Systems****	****	****- radiation damaged**
**AC Dipole****	****	****	****- MECO extinction**
**Strip-line Kickers****	****	****- MECO extinction**
**AGS injection kickers****	****- higher intensity**
**25 MHz RF Cavity****	****	****- KOPIO bunch widths**
**100 MHz RF Cavity****	****	****- KOPIO bunch widths**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Impedance Reduction

**Fewer RC Networks and more shorted vacuum chambers**
**New RC Networks capable of higher power dissipation **
**New Electrostatic septum**
**Fewer ceramic coated vacuum flanges**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## CFI Collaboration

**The costs associated with the AGS upgrade for KOPIO are partly being covered by the Canadian collaboration**.
-  25 MHz and 100 MHz micro-bunching radio frequency cavities
-  A5 kicker magnet upgrades (+A10 modules)
-  Beam and accelerator physics studies (+simulations)
-  KOPIO beam line and production target
**AGS upgrades for KOPIO – overall budget (2001 $’s).**

|  | Total Cost
Can. $million  | US Contribution
Can. $million | Canadian Contribution (CFI)
Can. $million |
| --- | --- | --- | --- |
| Micro-bunching | 5.310 | 3.662 | 1.648 |
| Kickers | 6.824 | 1.619 | 5.205 |
| Beam development | 1.000 | 0.625 | 0.375 |
| Proton beam line | 1.946 | 1.946 | 0 |
| Total | 15.280 | 7.850 | 7.228 |

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## BTA Upgrade to 2 GeV (CFI funded)

**BTA Upgrade to 2 GeV ****(CFI funded)**

- Upgrade BTA + AGS injection from 1.9 GeV with large mismatch to 2.0 GeV without mismatch  	improved space charge limit and no halo        	formation ( “1 ms loss”)
- All elements except kickers are OK
- AGS injection kicker: add kicker modules

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## AGS Modifications

|  | H99%,N ( mm-mrad) | V99%,N ( mm-mrad) |
| --- | --- | --- |
| Pre-Booster (1980)
200 MeV  injection | 49 | 60 |
| Post-Booster (1997)
1.94 GeV injection | 99 | 85 |

-  _**Measured extracted beam emittance with High Intensity Protons**_

| Parameter | Value | Units |
| --- | --- | --- |
| Peak Intensity | 74.0 | 1012 protons/pulse |
| Extraction Efficiency | 97-98 | % |
| Spill Lengths | 1.8 – 5.8  | Seconds |
| Working Point | 8.667 / 8.78 | Horiz./Vert. Tune |
| Normalized Chromaticity | -2.5 / 0.05 | Horiz./Vert. Chrom. |
| Extraction Momentum | 25.5   | GeV/c |

_**Normal SEB AGS Parameters**_

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## AGS Modifications

| Parameter | H20 septum | F5 septum | F10 septum |
| --- | --- | --- | --- |
| H [m] | 12.0 – 19.9 | 22.1 | 19.9 – 12.0 |
| V [m] | 19.9 – 12.0 | 10.5 | 12.0 – 19.9 |
| Horz. Gap [mm] | 10.0 | 44.45 | 38.1 |
| Vert. Gap [mm] | 20.0 | 17.8 | 19.1 |
|  | 27 | 27 | 27 |
| AH [-mm-mrad] | 1.25 | 22.35 | 18.24 |
| AV [-mm-mrad] | 5.03 | 7.54 | 4.58 |
| AHN [-mm-mrad] | (34)* | 603 | 492 |
| AVN [-mm-mrad] | 136 | 204 | 124 |

- * Beam size depends on step size, acceptance not a significant parameter.

_**Existing extraction channel acceptance at 25.5 GeV/c**_

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## AGS Modifications

| Parameter | H20 septum | F5 septum | F10 septum |
| --- | --- | --- | --- |
| H [m] | 12.0 – 19.9 | 22.1 | 19.9 – 12.0 |
| V [m] | 19.9 – 12.0 | 10.5 | 12.0 – 19.9 |
| Horz. Gap [mm] | 10.0 | 44.45 | 38.1 |
| Vert. Gap [mm] | 20.0 | 17.8 | 19.1 |
|  | 8.6 | 8.6 | 8.6 |
| AH [-mm-mrad] | 1.25 | 22.35 | 18.24 |
| AV [-mm-mrad] | 5.03 | 7.54 | 4.58 |
| AHN [-mm-mrad] | (11)* | 192 | 157 |
| AVN [-mm-mrad] | 43 | 65 | 39 |

- * Beam size depends on step size, acceptance not a significant parameter.

_**Existing extraction channel acceptance at 7.5 GeV/c**_

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## AGS Extraction Modifications

** ****New Electrostatic Septum**
** ****larger vertical aperture**
** ****variable horizontal aperture**
** ****reduce impedance**
** ****longer life and higher reliability**

- Cross section of existing electrostatic septum.

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## AGS Extraction Modifications

- CERN Electrostatic septum

- BNL Electrostatic septum

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## AGS Extraction Modifications

** ****New Thick Septum**
** ****Larger Vertical Aperture**
** ****Combined function**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## AGS Extraction Modifications

-  _**Modifications for MECO**_

- Histogram = QVT
- Dots = scalar counts

- Beam Intensity vs. Time modulo 1.35 s during test with E871 trigger

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## RF Modulated Dipole + Lambertson Magnets + Small Production Target
Filled buckets
Arrival at RF dipole coincides with maximum field in the dipole
Beam is deflected into shielded channels in Lambertsons
Beam arriving out-of-time (empty buckets)
Receives less than maximal deflection in dipole
Enters diversion channels in Lambertsons
Counters placed downstream of the Lambertsons serve as a monitor

- Filled buckets
- Arrival at RF dipole coincides with maximum field in the dipole
- Beam is deflected into shielded channels in Lambertsons
- Beam arriving out-of-time (empty buckets)
- Receives less than maximal deflection in dipole
- Enters diversion channels in Lambertsons
- Counters placed downstream of the Lambertsons serve as a monitor

**MECO: Gap Cleaning in the Beam Transport Line**

- Nominally filled buckets receive the maximum kick

- Unfilled buckets receive negative kick

- Time

- RFMM Field Strength

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Micro-bunched slow extraction

**Micro-bunched slow extraction**

- Time

- Extraction resonance

- Frequency

- Empty buckets generate energy modulation of debunched beam
- Higher cavity voltage and/or smaller P/P    shorter bunches
- Need ~200 ps bunches every 40 ns

- Debunched beam

- 40 ns

- 200 ps

**AGS Extraction Modifications**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Simulation of the extraction process for 25+100 MHz RF cavities.
Impose a high frequency longitudinal oscillation on the beam.
Slowly bring the beam into resonance (82/3).
Beam is forced through the narrow phase region between the RF buckets.
Adding the 100MHz harmonic cavity sharpens up the phase region in resonance.

**Simulation of the extraction process for 25+100 MHz RF cavities.**
**Impose a high frequency longitudinal oscillation on the beam.**
**Slowly bring the beam into resonance (8****2****/****3****).**
**Beam is forced through the narrow phase region between the RF buckets.**
**Adding the 100MHz harmonic cavity sharpens up the phase region in resonance.**

- Extracted
- particles

- 25 MHz fundamental
- + 100 MHz harmonic

- Extraction
- Region

**AGS Extraction Modifications**

-  _**Modifications for KOPIO: Simulations**_

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Test Results: Microbunch Width

- 93 MHz cavity at 22 kV
- gave **s** = 217 ps.

**Microbunch time, in ns**

- 93 MHz cavity at 22 kV
- gave **s** = 240 ps.

**Microbunch time, in ns**

- Data

- Simulation

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction and Switchyard Modifications

**Existing Switchyard**
** ****Designed in late 1970’s when peak intensities were < 20x10****12**** p/cycle**
** ****Aperture limitations**
** ****Designed to achieve 4 way split beams**
** ****6 movable elements & 7 tilted magnets**
** ****Many elevation shifts made to accomplish split beams to separate lines**
**New Switchyard**
** ****Aperture limitations removed**
** ****No Electrostatic splitters, single transport beams only**
** ****No movable magnets and no tilted magnets**
** ****No elevation shifts**
** ****Greatly simplified operation**
** ****Includes 3 Beam Plugs, to isolate areas for access**
** ****Includes collimation for halo removal and improve extinction **

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction and Switchyard Modifications

| Existing Switchyard | New Switchyard |
| --- | --- |
| Aperture limitations | Aperture limitations removed |
| 3 Electrostatic splitters | No Electrostatic splitters |
| 6 movable magnets | No movable magnets |
| Many elevation shifts | No elevation shifts |
| Existing A line | New A line |
| 28 elements | 10 elements |
| 4 vertical bends | 2 vertical bends |
| 2 tilted magnets | No tilted magnets |
| Existing B line | New B line |
| 32 elements | < 20 elements |
| 4 vertical bends | No vertical bends |
| 3 tilted magnets | No tilted magnets |
| Existing Instrumentation | New Instrumentation |
| 9 flags, all movable, with 9 cameras | Profiles from non-movable EPM’s |
| ~ 70 loss monitors with gas lines | ~ 30 loss monitors with gas lines |

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction and Switchyard Modifications

**Slow Extraction and Switchyard Modifications**

**EXISTING SWITCHYARD**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction and Switchyard Modifications

- h

- v

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## New Switchyard

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Summary

**AGS peak throughput achieved is 22 Tp/sec. RSVP Goal is 40 TP/sec.**
**To reach the throughput goals of the two RSVP experiments requires R&D, infrastructure improvements, and Beam Development Time.**
**Operation of a high intensity, high beam power accelerator requires**
** ****Managing Occupational dose to workers (ALARA)**
** ****minimization of environmental impact**
** ****reducing the risk of equipment failure due to radiation damage**
** ****reducing the risk of fire and exposure to hazards**
** ****minimizing the impact on other experimental programs **
**C-AD is committed to the success of RSVP and the infrastructure improvements program is focused on achieving RSVP goals.**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Supplemental Material

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Overview of AGS Slow Extraction

- 1/3 integer resonant extraction system

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## High Intensity Slow Extraction

**70 TP Slow extracted beam observations. Vertical Chromaticity is kept positive after transition.  **

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction and Switchyard Modifications

**Slow Extraction and Switchyard Modifications**

**EXISTING SWITCHYARD**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction and Switchyard Modifications

**Slow Extraction and Switchyard Modifications**

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## New Switchyard

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction Dynamics

- A particle with a magnetic rigidity *B**** *receives (thin lens) kicks by a sextupole of length *L*,

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction Dynamics

- h

- stable

- unstable

*X’*

*X*

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction Dynamics

- Stable region

- Unstable region

- Extraction Methods:
- Widen stopband by increasing S
- Move particles into resonance by changing betatron tune (AGS).
- Increase particle amplitudes until it encounters the unstable region (rf knockout method).

- Distrib. Of particles

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction: ES Phase Space

- 1 cm

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Slow Extraction: Thin MS Phase Space

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Spill and Ripple

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Spill and Ripple

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Spill and Ripple

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Spill and Ripple

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Spill and Ripple

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## MECO: Bunch Intensity Limits

- The present per-bunch intensity limit comprises
- Space charge effects during accumulation, 800 ms nominally                                                                                            133 ms (one Booster cycle) for MECO
- Momentum aperture constriction at transition prevents use of full longitudinal acceptance of AGS                                                                 MECO running below transition removes this constraint
- Machine studies are required to determine whether the above factors are sufficient to achieve 20 Tp / bunch
- We may face overall intensity limits due to ALARA concerns operating at 40 Tp/s.

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Early Extinction Measurements

**Early Extinction Measurements**

- Initial test at 24 GeV/c with one bucket in the AGS yielded <10-6 extinction between buckets and 10-3 in unfilled buckets
- A second test at 7.4 GeV/c with a single bucket found <10-7 extinction
- Test time was insufficient in either case to optimize the extinction during the test
- It is possible that careful tuning alone will suffice to achieve <10-9  but we are conservatively assuming that it will not

- Beam Intensity vs. Time modulo 1.35 s during test with E871 trigger

- Histogram = QVT
- Dots = scaler counts

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Stripline AC dipole at 80 kHz excites coherent vertical betatron resonance
Fast (100 ns) kickers cancel AC dipole at the bunches
Kicker duty factor is low 100 ns / 2.7s = 4% 

Concept tested                                                                                                             in FY98 using                                                                                              existing AC dipole                                                                                       and kickers 

- Fast (100 ns) kickers cancel AC dipole at the bunches
- Kicker duty factor is low 100 ns / 2.7s = 4%
- Concept tested                                                                                                             in FY98 using                                                                                              existing AC dipole                                                                                       and kickers

**AGS Internal Extinction**

- Filled Bunches

- Fast Kicker Pulses

- AC Dipole Signal

- 2 ****s

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## FY98 AGS Extinction Tests

**FY98 AGS Extinction Tests**

- AC Dipole On

- AC Dipole
- (reduced voltage)

- Kicker

- Beam Intensity
- AC Dipole drives beam out of the machine in 20 ms

- 10 ms

- Kicker restores beam (note that it is too weak to do so completely)

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements

## Reiterating MECO Beam Requirements

- Beam momentum = 7.5 GeV/c
- Two bunches in the AGS at 180 ( = 1.35 s) with 20 Tp each
- Beam slow extracted over 0.5 s in < 50 ns wide bunches with a                      1.0 s cycle time
- Inter-bunch extinction ratio, 1:109 or better
- Narrow focus (radius 1 mm) beam on a small cross-section target with minimal material around it
- Flexibility in the steering to allow for beam on target with MECO solenoids in either polarity
- At a minimum (in the ideal case) 4 ×1020 protons delivered, reaching design sensitivity could require 50% more

- Kevin Brown, BNL                    AGS/Booster/Switchyard Modifications and RSVP Beam Requirements