# Presentation: 436989

## Fermilab/NICADD Photoinjector Laboratory (FNPL): Collaborative R&D

***Gerald C. Blazey***
**	*****Northern Illinois Center for Accelerator and Detector Design ***
***(http://nicadd.niu.edu)***
***Northern Illinois University***

***A guideline reminder:***
***Stay clear of political issues***
***Interdisciplinary***
***Feel free to express ignorance***

## FNPL

**FNPL**
**Electron source @ A0 **
**Jointly operated by Fermilab/NICADD**
**Beam Physics **
**International Facility (Chicago, Georgia, Michigan, NIU, Rochester, Fermilab, DESY, CERN, LBL)**

## Dissertations

* **E. R. Colby, Ph.D., UCLA, 1997. Design, Construction, and Testing of a Radiofrequency Electron Photoinjector for the Next Generation Linear Collider*. RF guns currently operating at Fermilab and DESY were constructed in the course of this work.
-  *A. Fry, Ph.D., Rochester, 1996. Novel Pulse Train Glass Laser for RF Photoinjectors.* Design and initial performance of the laser at the Fermilab photoinjector.
-  *S. Fritzler, Diplomarbeit, Darmstadt, 2000*. This thesis covers the *first observation of channeling radiation in the high flux environment* of A0, and extends observations as a function of bunch charge two orders of magnitude higher than any earlier measurement.
-  *M. Fitch, Ph.D., Rochester, 2000. Electro-Optic Sampling of Transient Electric Fields from Charged Particle Beams*. In addition to the discussion and measurement of wakefields induced by bunch passage through the photoinjector, further data on laser and injector performance is given.
-  *J.-P. Carneiro, Ph.D., Universite de Paris-Sud, 2001. Etude experimental du photo-injecteur de Fermilab*. This is a thorough documentation of the performance of the photoinjector, including comparison with the predictions of E. Colby.
** ****Current**
* **D.Bollinger, NIU, *Plasma Acceleration
* **R.Tikhoplav, Rochester, *Laser Acceleration.
* **Y-e Sun, Chicago, *Flat Beams.

_**Dissertations**_

## The plasma wake-field acceleration experiment

- Decelerated electrons down to ~3 MeV:

- Accelerated electrons up to 20.3 MeV

- Simulation result:
- final energy spectrum

- Parameters:
-  Charge: 6-8 nC
-  Bunch length: < 1 mm RMS
-  Plasma: L=8cm, 10  /cc density
-  Initial energy: 13.8 MeV
-  Acceleration gradient: 72 MeV/m

- 14

## LASER ACCELERATION OF ELECTRONS

- Study the possibilities of using a laser beam to accelerate charged particles in a wave guide structure with dimensions much larger than the laser wavelength
- The laser operates in the TEM01* mode which provides the largest possible longitudinal component of the electric field.
- For 34 TW of laser power (the maximum that that can be supported by the structure) the accelerating field *E**a**=*0.54 GV/m.

## Flat Beams

- Flat beam generation could simplify requirements for
- Linear collider electron damping rings!

_**Flat Beams**_

## Energy Fragmentation from Bunch 

_**Energy Fragmentation from Bunch **_
_**Compression **_
- (taken 6 Feb 02 via remote operation from DESY-GAN!)

- Beam Energy ~ 15 MeV, Bunch Charge ~1 nC
- Compression essential for FELs

## Global Accelerator Network

**Successfully operated the photoinjector from DESY and LBNL – and a major milestone.**
**A web based system in initial stages of development**
**Would benefit from the type of controls experience common to experiments**
**Remote operation**
**Transmission of data**
**Standard analysis packages**
**Contact Kai Desler (desler@fnal.gov)**

## Additional Dissertations

- http://nicadd.niu.edu/fnplres.html

- Electron-Beam Diagnostics
-   electro-optic crystal
-   Michelson interferometer
-   diffraction-radiation
-   deflecting srf cavity
-   Superconducting RF Cavities
-   “kaon-separator” (deflecting) cavity
-   “beam-shaper” (accelerating) cavity
-   RF Gun
-   high-duty-factor (srf?)
-   polarized beam
-   dark current and photocathode
-   Fundamental Studies of Space Charge, Coherent Synchrotron Radiation

## Superconducting RF

**Measurement of CP violation in K****+**** ********+******** (fixed target experiment E921) requires a few 10****14**** K****+**
**We will create a pure K****+**** beam with ~ 6 meters of SCRF cavities operating at 3.9GHz in TM****110**** at 5MV/m P****TRANS**
**One and three cell structures have been run up to B****MAX**** of 85 to 104 mT on inside surface – compare TESLA TM****010**** mode (110 mT at 25 MV/m E****ACC****); CKM separators need 77 mT**
**Contact Helen Edwards (hedwards@fnal.gov)**

- 13-cell prototype deflecting cavity
*Nb shaped at FNAL, e-beam welded at nearby contractor, chemical and heat treatment for prototypes has been done at Jefferson Lab.*

## Proposal for a High-brightness Photoinjector 

**A collaboration modeled on large detector collaborations for the construction and operation of a high-brightness electron beam at Fermilab.**
**Five year construction, then operation**
**Advanced beam research and machine development.**
**The collaboration presently includes seven universities and three laboratories.   **
**An Expression of Intent submitted 02/11/02 to FNAL, ANL, LBNL, DOE, and NSF asking for encouragement to begin a design report. **
**Have encouragement from FNAL, ANL, LBNL.**

## Motivation

_**Fundamental beam and accelerator physics**_
**Wakefield & laser acceleration.**
**Bunch Compression.**
**Flat & Polarized Beams.**
**Emittance Reduction.**
**All of which will promotes growth and innovation through university training of accelerator physicists.**
_**Support for the new generation of linear colliders, FELs, and synchrotron radiation sources (1 micron emittance and <270 micron pulses)**_
**Demonstrate that injector specifications can be met.**
**Platform to study generation of required beams.**
**Develop expertise and infrastructure for LC efforts.**
_**Utilizes superconducting RF cavities and will foster Midwest and national development of the technology.**_

## Notional Layout of Photoinjector

_**Notional Layout of Photoinjector**_
- (as envisioned by DESY)

_**Emittance ~1 micron, Bunch Length <270 microns**_
- Energy 140300 MeV

**Notes:**
Major components are: 
a drive laser that ejects electrons from the photocathode and delivers the requisite bunch train, 
 an electron gun that incorporates a 1.3 GHz copper RF cavity for rapid acceleration of the low-energy beam, 
 two cryomodules each housing eight TESLA SRF accelerating cavities
(4) a 3.9 GHz SRF accelerating section to improve the longitudinal phase-space of the beam prior to bunch compression, 
(5) an array of dipole magnets with which to compress the bunches, and 
(6) a section of electron-beam diagnostics.

## Major Components

**Drive laser (provides a flexible pulse structure and train) with a CsTe photocathode (high QE).**
**Emittance compensating solenoids.**
**A DESY donated 1.3 GHz, 8 cavity cryomodule (immediate acceleration reduces emittance growth due to space charge).**
**3****rd**** Harmonic superconducting RF section to correct non-linearities in longitudinal phase space.**
**Four-dipole compression stage.**
**Diagnostic & matching section.**
**A domestically developed cryomodule.**

## Collaboration

**Envision the laboratories (Fermilab, Argonne, LBNL, DESY) taking responsibility for larger projects.**
**Infrastructure (Fermilab)**
**RF Gun (ANL), High repetition RF Gun (LBNL)**
**Cryomodules (DESY, Pi3) **
**3****rd**** Harmonic (Fermilab/LBNL)**
**Compressor (Fermilab/ANL)**
**While the universities  (Chicago*, Michigan, NIU*, Northwestern*, Pennsylvania, Rochester, UCLA ) .**
**Contribute personnel to laboratory based projects**
**Take responsibility for smaller projects **
**Simulations**
**Laser **
**Diagnostics**
**An open collaboration****!**

***Members of Illinois Consortium for Accelerator Research**

## Simulations

**Need to simulate all aspects for the design proposal**
**Complete simulation of a photoinjector is done with several  separate packages (HOMDYN, ASTRA, PARMELA, etc...) each with limitations**
**Gun**
**3****rd**** Harmonic**
**Compressor**
**An integrated simulation would be a necessary step forward**
**Well suited to the skill set familiar to HEP types**
**Contact Court Bohn (clbohn@fnal.gov)**

## Laser Development

**An interesting instrument requires flexibility:**
**1 MHz train of up to 800 equal-amplitude pulses **
**1 mJ per pulse (0.8 J per macropulse) **
**1054 nm**
**1-40+ ps pulses**
**Clearly cross-disciplinary.**
**Contact Adrian Melissinos (meliss@pas.rochester.edu)**

## Conventional Diagnostics(both FNPL and Pi3)

**Faraday cup for bunch charge **
**Button beam-position monitors **
**Multi-slit transverse emittance **
**Optical-transition-radiation (OTR) viewers   **
**Dipole-magnet spectrometer for energy and energy spread **
**Michelson interferometer for longitudinal bunch profile **

## Interferometer(both FNPL and Pi3)

**A good example is development of an interferometer to measure pulse length**
**Intensity and frequency of emitted radiation is sensitive longitudinal distribution of charge.**
**With an interferometer the spectrum can be sampled and the bunch length measured.**
**To be designed and built at Georgia but help installing commissioning needed**

## Innovative Diagnostics(both FNPL and Pi3)

**Non-intercepting diagnostics**
**electro-optic crystal**
**diffraction radiation**
**improved beam-position monitors**
**micro-undulator **
**Future generations of interferometers  **
**Deflecting-mode cavity as spectrometer**
**Tomographic techniques**
**Many projects – talk to Court Bohn (clbohn@fnal.gov)**

## Conclusions

**FNPL offers immediate opportunities **
**Pi3 will strengthen HEP and the laboratories: **
**A collaborative model to promote accelerator physics (open to additional institutions).**
**Strengthens accelerator physics infrastructure.**
**Supports development of new technologies and machines.**
**Join!**
**Thanks to George and Dan**