# ⚛  L1 Principle — DESI-MSI — Desorption ElectroSpray Ionization Mass-Spec Imaging

**ID:** `L1-144` · **Status:** ⊙ Testnet (genesis catalog)

> **🌐 Domain:** Spectroscopy — *Ambient mass-spec imaging*
> **🎯 Problem class:** linear inverse count · **🧮 Solution space:** molecular surface map
> **📡 Carrier:** ion · **🌫 Noise:** shot poisson
> **⚖ Difficulty (δ):** 3 · **⛓ Block:** 41554228

---

## 🧠 1. Introduction

**DESI-MSI — Desorption ElectroSpray Ionization Mass-Spec Imaging** is a **linear inverse count** whose unknown lives in **molecular surface map** space, within the **Ambient mass-spec imaging** sub-domain of **Spectroscopy**.

Measurements consist of ions detected after acceleration or extraction via a **ambient ionization ms** sensing mechanism.

The forward operator applies, in order: L · spray · chargeddroplet operator; L · disperse · mass operator; detector accumulates flux over the exposure window.

Observations are corrupted by Poisson shot noise from quantum-limited detection. Linear regime at low analyte density; ion-suppression & matrix effects dominate at high concentration. Spray stability drift causes low-frequency artifacts in slow scans.

## ⚙ 2. Forward Model

Physical chain: **x** → L · spray · chargeddroplet → L · disperse · mass → Temporal integration → **y** (detector).

```
y = ∫_t dt `L.disperse.mass` `L.spray.chargeddroplet` x,    measurements ~ Poisson(αy)
```

**Measurement DAG:**

| Primitive | What it does |
|---|---|
| `L.spray.chargeddroplet` | L · spray · chargeddroplet operator |
| `L.disperse.mass` | L · disperse · mass operator |
| `int.temporal` | Detector accumulates flux over the exposure window |

## 🔬 3. Physics Fingerprint

| Property | Value |
|---|---|
| Domain | Spectroscopy |
| Sub domain | Ambient mass-spec imaging |
| Carrier | ion |
| Problem class | linear_inverse_count |
| Solution space | molecular_surface_map |
| Noise model | shot_poisson |
| Integration axis | mass_and_spatial |
| Difficulty delta | 3 |
| L dag | 2.7 |

## 📡 4. Measurement Model

Linear regime at low analyte density; ion-suppression & matrix effects dominate at high concentration. Spray stability drift causes low-frequency artifacts in slow scans.

| Metric | Value |
|---|---|
| Metric | concentration_NMSE |
| Secondary | spatial_resolution_um |

## 📏 5. Operating Range (Ω)

**Center problem class:** `desi_msi_mapping` · **Forward operator:** `desi_msi_forward`

**Center point:**

| Parameter | Unit | Value |
|---|---|---|
| H | px | 200 |
| K | — | 10 |
| W | px | 200 |
| N mz | — | 20000 |
| R mass | — | 30000 |
| Pixel um | µm | 100 |
| Ion suppression | — | 0.1 |

**Allowed bounds:**

| Parameter | Unit | Range |
|---|---|---|
| H | px | 32 – 1024 |
| K | — | 1 – 50 |
| W | px | 32 – 1024 |
| N mz | — | 1000 – 100000 |
| R mass | — | 5000 – 200000 |
| Pixel um | µm | 20 – 500 |
| Spray drift | — | 0.0 – 0.3 |
| Ion suppression | — | 0.0 – 0.8 |
| Pixel stitching error | — | 0.0 – 0.2 |
| Mass calibration error | — | 0.0 – 50 |
| Scan speed variability | — | 0.0 – 0.2 |

## 🎯 6. Tolerance (ε)

**Center tolerance:** NMSE 0.03

| Metric | Range |
|---|---|
| Nmse | 0.001 – 0.5 |

## ⚖ 7. Hardness Function

Hardness scales as **`epsilon_fn`** on **concentration_NMSE**, with κ = `500` and δ = `3`.

## 💾 8. Reference Dataset

- **primary** · weight 1.0 · IPFS _(not pinned yet)_

## 9. On-chain Registration

- **Chain hash:** `0xd480a9f7d0748d4c1b7e5ecff2b5a322b7b0d4a543b528db8313729714d97aef`
- **Chain tx hash:** `0xf62be37e39b2d642360ba2828f2dbece60824530cd08d852b7606e7b8f980c11`
- **Chain block:** `41554228`

---

## File Mapping

This bundle consists of: `L1-144.md`, `L1-144.json`.

| File | Role | How to regenerate |
|------|------|-------------------|
| `L1-144.md` | Source of truth — edit this | Human or LLM |
| `L1-144.json` | Structured metadata for the registry | LLM regenerates from the sections above |

**Prompt for your LLM after editing this Markdown:**

> Read the attached Markdown. Regenerate the sibling `.json` so every field matches.
> Preserve the schema documented in the rows above.
> Output each file in its own fenced code block tagged with the filename.
> Output only the JSON object.

_This Markdown was auto-synthesized from the catalog row for `L1-144`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._